> ## Documentation Index
> Fetch the complete documentation index at: https://hyperframes-fix-nested-composition-media-inpoint.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Camera Follow Captions

> One sentence written across a world far larger than the frame. Each word is sized against everything already written, so the block grows geometrically and the camera pulls back at a steady rate to keep landing the new word at the same size. Old words stay lit and simply become small.

export const VariablesExplorer = ({previewSrc, compositionId, compositionSrc, variables, children}) => {
  const SHIKI = {
    punct: {
      color: "rgb(31, 35, 40)",
      "--shiki-dark": "#808080"
    },
    tag: {
      color: "rgb(17, 99, 41)",
      "--shiki-dark": "#569CD6"
    },
    attr: {
      color: "rgb(5, 80, 174)",
      "--shiki-dark": "#9CDCFE"
    },
    equals: {
      color: "rgb(31, 35, 40)",
      "--shiki-dark": "#D4D4D4"
    },
    value: {
      color: "rgb(10, 48, 105)",
      "--shiki-dark": "#CE9178"
    }
  };
  const CSS = `
.hf-ve {
  --ve-fg: #18181b;
  --ve-muted: #71717a;
  --ve-line: #e4e4e7;
  --ve-surface: #ffffff;
  --ve-sunken: #fafafa;
  --ve-hover: #f4f4f5;
  --ve-on-bg: #18181b;
  --ve-on-fg: #ffffff;
  --ve-ring: rgba(24, 24, 27, 0.14);
  --ve-danger: #b42318;
}
:where(html.dark) .hf-ve {
  --ve-fg: #f4f4f5;
  --ve-muted: #a1a1aa;
  --ve-line: #27272a;
  --ve-surface: #18181b;
  --ve-sunken: #131316;
  --ve-hover: #27272a;
  --ve-on-bg: #f4f4f5;
  --ve-on-fg: #18181b;
  --ve-ring: rgba(244, 244, 245, 0.2);
  --ve-danger: #ff9d95;
}

.hf-ve-tabs {
  display: inline-flex;
  gap: 2px;
  padding: 3px;
  border: 1px solid var(--ve-line);
  border-radius: 9999px;
  background: var(--ve-sunken);
}
.hf-ve-tab {
  padding: 4px 12px;
  border-radius: 9999px;
  font-size: 12px;
  font-weight: 500;
  color: var(--ve-muted);
  background: transparent;
}
.hf-ve-tab[data-on="true"] {
  color: var(--ve-fg);
  background: var(--ve-surface);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.08);
}
.hf-ve-tab:hover:not([data-on="true"]) { color: var(--ve-fg); }

/* Not a grid. A grid row is as tall as its tallest cell, so a five-line snippet
   sat in the preview's 16:9 box with 300px of dead area under it. The inactive
   pane is taken out of flow instead — and stretches left/right rather than to
   inset 0, so the iframe keeps its own height. An iframe resized on every tab
   switch reflows the composition running inside it. */
.hf-ve-frame { position: relative; }
.hf-ve-cell { min-width: 0; }
.hf-ve-cell[data-on="false"] {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  visibility: hidden;
  pointer-events: none;
}
.hf-ve-preview {
  overflow: hidden;
  border: 1px solid var(--ve-line);
  border-radius: 12px;
}
/* CodeBlock carries the page margins (mt-5 mb-8) that separate it from prose,
   which is dead space inside a tab. Element plus two classes out-specifies a
   Tailwind utility without !important. */
.hf-ve-cell > div.code-block { margin: 0; }
/* The snippet wraps; the source does not.
   A value the reader has to read in full should not hide half of itself off the
   right edge, so the snippet pane wraps — what \`\`\`html wrap does for a fence.
   The width reset is the half that matters: the block's own <code> is sized to
   max-content, and content that never meets an edge never wraps.
   Source is left to scroll sideways like every other code block on the site.
   Wrapping it breaks its indentation, and a comment paragraph re-flowed to a
   narrow column reads worse than one the reader can scroll. */
.hf-ve-snippet .shiki,
.hf-ve-snippet .shiki code {
  white-space: pre-wrap;
  overflow-wrap: anywhere;
}
/* A composition source runs to several hundred lines, and an un-capped tab
   pushes the Customize panel off the screen. The cap goes on the scroll box
   rather than the block, so the filename and its copy button stay put; and it
   is a max-height, so a short source still hugs its own content and the dead
   area under it stays gone. */
.hf-ve-cell .code-block pre {
  max-height: 460px;
  overflow: auto;
}
/* Four classes deep because the rule being answered is three
   (\`html:not(.dark) .codeblock-light pre.shiki code\`), and a shorter selector
   silently loses to it. */
.hf-ve .hf-ve-snippet .code-block pre.shiki code {
  width: auto;
  min-width: 0;
}

.hf-ve-panel {
  margin-top: 12px;
  border: 1px solid var(--ve-line);
  border-radius: 12px;
}
.hf-ve-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 16px;
  border-bottom: 1px solid var(--ve-line);
}
.hf-ve-title {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ve-muted);
}
.hf-ve-grid {
  display: grid;
  gap: 16px 28px;
  padding: 16px;
}
@media (min-width: 640px) {
  .hf-ve-grid { grid-template-columns: 1fr 1fr; }
}
.hf-ve-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 6px;
}
.hf-ve-label { font-size: 14px; font-weight: 500; color: var(--ve-fg); }
.hf-ve-value {
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 12px;
  font-variant-numeric: tabular-nums;
  color: var(--ve-muted);
}
.hf-ve-desc {
  margin: 6px 0 0;
  font-size: 12px;
  line-height: 1.45;
  color: var(--ve-muted);
}

.hf-ve-btn {
  padding: 4px 10px;
  border: 1px solid transparent;
  border-radius: 8px;
  font-size: 12px;
  font-weight: 500;
  color: var(--ve-muted);
  background: transparent;
}
.hf-ve-btn:hover:not(:disabled) { color: var(--ve-fg); background: var(--ve-hover); }
.hf-ve-btn:disabled { opacity: 0.4; cursor: default; }

.hf-ve-field {
  width: 100%;
  height: 36px;
  padding: 0 12px;
  border: 1px solid var(--ve-line);
  border-radius: 8px;
  font-size: 14px;
  line-height: 1.4;
  color: var(--ve-fg);
  background: var(--ve-surface);
}
.hf-ve-field::placeholder { color: var(--ve-muted); }
.hf-ve-mono { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 13px; }

/* Focus, once, for every control here. A ring outside the border rather than a
   border colour alone: the border already carries the resting state, so
   recolouring it is a change a reader can miss. Nothing shifts, because the
   ring is a shadow. :focus-visible, so a pointer click does not light it up. */
.hf-ve-field:focus-visible,
.hf-ve-seg-btn:focus-visible,
.hf-ve-tab:focus-visible,
.hf-ve-btn:focus-visible,
.hf-ve-switch:focus-visible,
.hf-ve-swatch:focus-visible {
  outline: none;
  border-color: var(--ve-on-bg);
  box-shadow: 0 0 0 3px var(--ve-ring);
}
/* A range is a track, and ringing the track rings a pill the width of the
   panel. The thumb is the part that has focus, so the thumb is what says so. */
.hf-ve-range:focus-visible { outline: none; }
.hf-ve-range:focus-visible::-webkit-slider-thumb { box-shadow: 0 0 0 4px var(--ve-ring); }
.hf-ve-range:focus-visible::-moz-range-thumb { box-shadow: 0 0 0 4px var(--ve-ring); }
/* Safari still fires :focus for a click on a button, so the pair is kept. */
.hf-ve-field:focus { outline: none; border-color: var(--ve-on-bg); }

/* The enum branch above sends anything past four options here. No shipped item
   does today (every enum in the registry has two to four), so this is styled to
   the point of not looking foreign and no further — the chevron is one neutral
   grey rather than a per-theme pair, because a data URI cannot read a token. */
.hf-ve-select {
  appearance: none;
  -webkit-appearance: none;
  padding-right: 34px;
  background-image: url("data:image/svg+xml;charset=utf-8,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' fill='none' stroke='%2389898f' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='m4 6 4 4 4-4'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 10px center;
  cursor: pointer;
}

.hf-ve-seg {
  display: flex;
  padding: 2px;
  border: 1px solid var(--ve-line);
  border-radius: 8px;
}
.hf-ve-seg-btn {
  flex: 1;
  padding: 4px 8px;
  border-radius: 6px;
  font-size: 12px;
  font-weight: 500;
  color: var(--ve-muted);
  background: transparent;
}
.hf-ve-seg-btn:hover:not([data-on="true"]) { color: var(--ve-fg); background: var(--ve-hover); }
.hf-ve-seg-btn[data-on="true"] { color: var(--ve-on-fg); background: var(--ve-on-bg); }

/* A range, rebuilt. \`accent-color\` alone leaves the platform's hairline track,
   which reads as an unstyled browser part next to everything else here. Each
   engine names its parts differently and shares none of them, so the same
   track and thumb are written twice; a selector either engine cannot parse
   drops the whole rule, which is why they are never grouped. */
.hf-ve-range {
  width: 100%;
  height: 20px;
  appearance: none;
  -webkit-appearance: none;
  border: 0;
  border-radius: 9999px;
  background: transparent;
  cursor: pointer;
}
/* --ve-fill is set per render: painting progress on a native track means a
   two-stop gradient, and only the component knows where the value sits. */
.hf-ve-range::-webkit-slider-runnable-track {
  height: 6px;
  border-radius: 9999px;
  background: linear-gradient(
    to right,
    var(--ve-on-bg) var(--ve-fill, 0%),
    var(--ve-line) var(--ve-fill, 0%)
  );
}
.hf-ve-range::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 16px;
  height: 16px;
  margin-top: -5px;
  border: 2px solid var(--ve-on-bg);
  border-radius: 9999px;
  background: var(--ve-surface);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.14);
}
.hf-ve-range::-moz-range-track { height: 6px; border-radius: 9999px; background: var(--ve-line); }
.hf-ve-range::-moz-range-progress { height: 6px; border-radius: 9999px; background: var(--ve-on-bg); }
.hf-ve-range::-moz-range-thumb {
  width: 16px;
  height: 16px;
  border: 2px solid var(--ve-on-bg);
  border-radius: 9999px;
  background: var(--ve-surface);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.14);
}
/* Hover reads on the part being aimed at rather than on the whole strip: a
   track that darkens under the pointer says "click me and the thumb comes
   here", which is what a native range actually does. */
.hf-ve-range:hover::-webkit-slider-thumb { border-color: var(--ve-fg); }
.hf-ve-range:hover::-moz-range-thumb { border-color: var(--ve-fg); }

/* The number control, and the three things it used to leave unsaid.
 *
 * It could not say where the range ends, so a reader dragging \`stroke_width\`
 * had no idea whether 12 was nearly nothing or nearly everything: the ends now
 * carry min and max.
 *
 * It could not say where the author left the knob, which is the one reference
 * point a panel built around deviating from the author's choice needs: a mark
 * on the track is the default, and a double click puts the value back on it.
 *
 * And it printed the value in the label row, a fixed distance from a thumb that
 * moves, so reading a drag meant looking in two places at once. The value rides
 * the thumb instead.
 *
 * Still a real <input type="range">. Every custom slider on the web reimplements
 * keyboard stepping, touch, and the screen-reader contract, and most of them do
 * one of the three badly; none of what is added here needed the element
 * replaced. Nothing moves that a finger is not moving: the value tracks the
 * pointer because it is the pointer's own readout, and the only transition is
 * the colour one every other control here shares. */
.hf-ve-slider {
  display: grid;
  gap: 1px;
}
.hf-ve-ruler {
  position: relative;
  height: 17px;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 11px;
  font-variant-numeric: tabular-nums;
  line-height: 17px;
  color: var(--ve-muted);
}
.hf-ve-bound {
  position: absolute;
  top: 0;
}
.hf-ve-bound[data-end="min"] { left: 0; }
.hf-ve-bound[data-end="max"] { right: 0; }
/* An end steps aside rather than being overprinted by the value arriving on
   top of it. Visibility, not opacity: there is no fade here, the label is
   either the thing being read or it is out of the way. */
.hf-ve-ruler[data-near="min"] .hf-ve-bound[data-end="min"],
.hf-ve-ruler[data-near="max"] .hf-ve-bound[data-end="max"] {
  visibility: hidden;
}
/* translateX is centring, not motion: the readout is as wide as its own digits
   and has to hang half of that either side of the thumb. */
.hf-ve-readout {
  position: absolute;
  top: 0;
  left: calc(var(--ve-fill, 0%) + var(--ve-fill-nudge, 0px));
  transform: translateX(-50%);
  color: var(--ve-fg);
  font-weight: 600;
  white-space: nowrap;
}
.hf-ve-track {
  position: relative;
  display: block;
}
.hf-ve-range { display: block; }
.hf-ve-default {
  position: absolute;
  top: 5px;
  left: calc(var(--ve-default, 50%) + var(--ve-default-nudge, 0px));
  width: 2px;
  height: 10px;
  margin-left: -1px;
  border-radius: 1px;
  background: var(--ve-muted);
  pointer-events: none;
}

/* A switch, for the boolean type. It used to fall through to the text input at
   the end of control(), which asked the reader to type the word "true". */
.hf-ve-switch {
  display: inline-flex;
  align-items: center;
  width: 40px;
  height: 24px;
  padding: 2px;
  border: 1px solid var(--ve-line);
  border-radius: 9999px;
  background: var(--ve-sunken);
  cursor: pointer;
}
.hf-ve-switch[data-on="true"] { border-color: var(--ve-on-bg); background: var(--ve-on-bg); }
.hf-ve-switch-dot {
  width: 18px;
  height: 18px;
  border-radius: 9999px;
  background: var(--ve-surface);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.18);
}
.hf-ve-switch[data-on="true"] .hf-ve-switch-dot {
  background: var(--ve-on-fg);
  transform: translateX(16px);
}

/* The SVG import control: the same text field, with a way to fill it.
 *
 * The whole block is the drop target, not just the field, so a file let go over
 * the button lands too. It says so by taking the same border colour a focused
 * field takes, which is the one feedback channel this panel has left.
 *
 * A bare <input type="file"> is unlabelled, unstyleable and reads as "No file
 * chosen" next to controls that carry their own value, so the real input is
 * taken out of the layout and the tab order and a button in front of it is what
 * a reader sees and what a keyboard reaches. Hidden with size and opacity
 * rather than display:none, because an input that is not rendered at all is one
 * some browsers decline to open a picker for. */
.hf-ve-drop {
  display: grid;
  gap: 8px;
}
.hf-ve-drop[data-over="true"] .hf-ve-dropzone {
  border-color: var(--ve-on-bg);
  border-style: solid;
}

/* The import is the action almost everyone wants: a reader arrives with a
   shape, not with path data. A dashed target reads as "put a file here" on
   sight, where a button beneath a field of coordinates read as an afterthought
   to the coordinates. */
.hf-ve-dropzone {
  display: grid;
  justify-items: center;
  gap: 6px;
  padding: 18px 12px;
  border: 1px dashed var(--ve-line);
  border-radius: 10px;
  background: var(--ve-surface);
  text-align: center;
}
.hf-ve-dropzone .hf-ve-btn {
  padding: 7px 16px;
  font-size: 13px;
  color: var(--ve-fg);
  border-color: var(--ve-line);
  background: var(--ve-bg);
}
.hf-ve-dropzone .hf-ve-btn:hover:not(:disabled) { background: var(--ve-hover); }

/* Path data stays reachable, but a reader has to ask for it. A native details
   element rather than our own toggle, so it opens with the keyboard and is
   announced as expandable without any wiring. */
.hf-ve-advanced > summary {
  font-size: 12px;
  color: var(--ve-muted);
  cursor: pointer;
  list-style: none;
  padding: 2px 0;
}
.hf-ve-advanced > summary::-webkit-details-marker { display: none; }
.hf-ve-advanced > summary::before { content: "▸ "; }
.hf-ve-advanced[open] > summary::before { content: "▾ "; }
.hf-ve-advanced > summary:hover { color: var(--ve-fg); }
.hf-ve-advanced .hf-ve-field { margin-top: 6px; }
.hf-ve-file {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
  pointer-events: none;
}
.hf-ve-note {
  margin: 0;
  min-width: 0;
  font-size: 12px;
  line-height: 1.4;
  color: var(--ve-muted);
}
.hf-ve-note[data-tone="error"] { color: var(--ve-danger); }
.hf-ve-note[data-tone="ok"] { color: var(--ve-fg); }

.hf-ve-swatch {
  width: 40px;
  height: 32px;
  flex-shrink: 0;
  padding: 2px;
  border: 1px solid var(--ve-line);
  border-radius: 8px;
  background: var(--ve-surface);
  cursor: pointer;
}

/* Nothing here moves.
 *
 * A press-down scale on every button and field, a scale-in on the tab panes, a
 * springing switch knob and a growing slider thumb were all flourish: the
 * control had already told you what it did by changing colour, and the motion
 * was a second, slower answer to a question already settled. What is left is
 * one colour transition, short enough to read as immediate and long enough not
 * to flicker. A control here may change colour; it does not move.
 *
 * Which is also why there is no prefers-reduced-motion block any more. There is
 * no motion left to reduce. */
.hf-ve-tint {
  transition:
    background-color 100ms ease,
    border-color 100ms ease,
    color 100ms ease;
}
`;
  const isSvgPathData = value => typeof value === "string" && (/^\s*[Mm]\s*-?[\d.]/).test(value);
  const parsePathData = d => {
    const source = String(d);
    const arity = {
      M: 2,
      L: 2,
      H: 1,
      V: 1,
      C: 6,
      S: 4,
      Q: 4,
      T: 2,
      A: 7,
      Z: 0
    };
    const commands = [];
    let at = 0;
    let code = "";
    const separator = () => {
      while (at < source.length && (/[\s,]/).test(source[at])) at += 1;
    };
    const digits = () => {
      while (at < source.length && source[at] >= "0" && source[at] <= "9") at += 1;
    };
    const number = () => {
      separator();
      const start = at;
      if (source[at] === "+" || source[at] === "-") at += 1;
      digits();
      if (source[at] === ".") {
        at += 1;
        digits();
      }
      if (source[at] === "e" || source[at] === "E") {
        at += 1;
        if (source[at] === "+" || source[at] === "-") at += 1;
        digits();
      }
      const text = source.slice(start, at);
      const value = Number(text);
      if (text === "" || !Number.isFinite(value)) {
        throw new Error(`expected a number at character ${start + 1}`);
      }
      return value;
    };
    const flag = () => {
      separator();
      const character = source[at];
      if (character !== "0" && character !== "1") {
        throw new Error(`expected an arc flag at character ${at + 1}`);
      }
      at += 1;
      return Number(character);
    };
    separator();
    while (at < source.length) {
      const character = source[at];
      if ((/[a-zA-Z]/).test(character)) {
        if (arity[character.toUpperCase()] === undefined) {
          throw new Error(`unknown command "${character}"`);
        }
        code = character;
        at += 1;
      } else if (code === "") {
        throw new Error("path data must open with a command");
      } else if (code === "M" || code === "m") {
        code = code === "M" ? "L" : "l";
      } else if (code === "Z" || code === "z") {
        throw new Error(`expected a command at character ${at + 1}`);
      }
      const letter = code.toUpperCase();
      const args = [];
      if (letter === "A") {
        args.push(number(), number(), number(), flag(), flag(), number(), number());
      } else {
        for (let taken = 0; taken < arity[letter]; taken += 1) args.push(number());
      }
      commands.push({
        code,
        args
      });
      separator();
    }
    if (commands.length === 0) throw new Error("path data is empty");
    return commands;
  };
  const normalisePathData = commands => {
    const out = [];
    let x = 0;
    let y = 0;
    let startX = 0;
    let startY = 0;
    let cubicControl = null;
    let quadraticControl = null;
    for (const {code, args} of commands) {
      const letter = code.toUpperCase();
      const relative = code !== letter;
      const dx = relative ? x : 0;
      const dy = relative ? y : 0;
      const pairs = values => {
        const mapped = [];
        for (let index = 0; index + 1 < values.length; index += 2) {
          mapped.push(values[index] + dx, values[index + 1] + dy);
        }
        return mapped;
      };
      let nextCubic = null;
      let nextQuadratic = null;
      if (letter === "M") {
        const [px, py] = pairs(args);
        out.push({
          code: "M",
          args: [px, py]
        });
        x = px;
        y = py;
        startX = px;
        startY = py;
      } else if (letter === "L") {
        const [px, py] = pairs(args);
        out.push({
          code: "L",
          args: [px, py]
        });
        x = px;
        y = py;
      } else if (letter === "H") {
        x = args[0] + dx;
        out.push({
          code: "L",
          args: [x, y]
        });
      } else if (letter === "V") {
        y = args[0] + dy;
        out.push({
          code: "L",
          args: [x, y]
        });
      } else if (letter === "C") {
        const points = pairs(args);
        out.push({
          code: "C",
          args: points
        });
        nextCubic = [points[2], points[3]];
        x = points[4];
        y = points[5];
      } else if (letter === "S") {
        const points = pairs(args);
        const first = cubicControl ? [2 * x - cubicControl[0], 2 * y - cubicControl[1]] : [x, y];
        out.push({
          code: "C",
          args: [...first, ...points]
        });
        nextCubic = [points[0], points[1]];
        x = points[2];
        y = points[3];
      } else if (letter === "Q") {
        const points = pairs(args);
        out.push({
          code: "Q",
          args: points
        });
        nextQuadratic = [points[0], points[1]];
        x = points[2];
        y = points[3];
      } else if (letter === "T") {
        const points = pairs(args);
        const control = quadraticControl ? [2 * x - quadraticControl[0], 2 * y - quadraticControl[1]] : [x, y];
        out.push({
          code: "Q",
          args: [...control, ...points]
        });
        nextQuadratic = control;
        x = points[0];
        y = points[1];
      } else if (letter === "A") {
        const endX = args[5] + dx;
        const endY = args[6] + dy;
        out.push(...arcToCubics(x, y, args[0], args[1], args[2], args[3], args[4], endX, endY));
        x = endX;
        y = endY;
      } else if (letter === "Z") {
        out.push({
          code: "Z",
          args: []
        });
        x = startX;
        y = startY;
      }
      cubicControl = nextCubic;
      quadraticControl = nextQuadratic;
    }
    return out;
  };
  const arcToCubics = (x1, y1, rx, ry, rotation, largeArc, sweep, x2, y2) => {
    if (x1 === x2 && y1 === y2) return [];
    let radiusX = Math.abs(rx);
    let radiusY = Math.abs(ry);
    if (radiusX === 0 || radiusY === 0) return [{
      code: "L",
      args: [x2, y2]
    }];
    const phi = rotation * Math.PI / 180;
    const cosPhi = Math.cos(phi);
    const sinPhi = Math.sin(phi);
    const midX = (x1 - x2) / 2;
    const midY = (y1 - y2) / 2;
    const primeX = cosPhi * midX + sinPhi * midY;
    const primeY = -sinPhi * midX + cosPhi * midY;
    const oversize = primeX * primeX / (radiusX * radiusX) + primeY * primeY / (radiusY * radiusY);
    if (oversize > 1) {
      const grow = Math.sqrt(oversize);
      radiusX *= grow;
      radiusY *= grow;
    }
    const denominator = radiusX * radiusX * primeY * primeY + radiusY * radiusY * primeX * primeX;
    const numerator = radiusX * radiusX * radiusY * radiusY - radiusX * radiusX * primeY * primeY - radiusY * radiusY * primeX * primeX;
    const factor = (largeArc === sweep ? -1 : 1) * Math.sqrt(Math.max(0, numerator) / denominator);
    const centrePrimeX = factor * radiusX * primeY / radiusY;
    const centrePrimeY = -factor * radiusY * primeX / radiusX;
    const centreX = cosPhi * centrePrimeX - sinPhi * centrePrimeY + (x1 + x2) / 2;
    const centreY = sinPhi * centrePrimeX + cosPhi * centrePrimeY + (y1 + y2) / 2;
    const angle = (ux, uy, vx, vy) => {
      const length = Math.hypot(ux, uy) * Math.hypot(vx, vy);
      const cosine = length === 0 ? 1 : Math.min(1, Math.max(-1, (ux * vx + uy * vy) / length));
      return (ux * vy - uy * vx < 0 ? -1 : 1) * Math.acos(cosine);
    };
    const fromX = (primeX - centrePrimeX) / radiusX;
    const fromY = (primeY - centrePrimeY) / radiusY;
    const toX = (-primeX - centrePrimeX) / radiusX;
    const toY = (-primeY - centrePrimeY) / radiusY;
    const start = angle(1, 0, fromX, fromY);
    let sweptAngle = angle(fromX, fromY, toX, toY);
    if (!sweep && sweptAngle > 0) sweptAngle -= 2 * Math.PI;
    if (sweep && sweptAngle < 0) sweptAngle += 2 * Math.PI;
    const steps = Math.max(1, Math.ceil(Math.abs(sweptAngle) / (Math.PI / 2)));
    const step = sweptAngle / steps;
    const handle = 4 / 3 * Math.tan(step / 4);
    const at = t => [centreX + radiusX * Math.cos(t) * cosPhi - radiusY * Math.sin(t) * sinPhi, centreY + radiusX * Math.cos(t) * sinPhi + radiusY * Math.sin(t) * cosPhi];
    const slope = t => [-radiusX * Math.sin(t) * cosPhi - radiusY * Math.cos(t) * sinPhi, -radiusX * Math.sin(t) * sinPhi + radiusY * Math.cos(t) * cosPhi];
    const out = [];
    for (let index = 0; index < steps; index += 1) {
      const from = start + index * step;
      const to = from + step;
      const [ax, ay] = at(from);
      const [bx, by] = at(to);
      const [aSlopeX, aSlopeY] = slope(from);
      const [bSlopeX, bSlopeY] = slope(to);
      out.push({
        code: "C",
        args: [ax + handle * aSlopeX, ay + handle * aSlopeY, bx - handle * bSlopeX, by - handle * bSlopeY, bx, by]
      });
    }
    const last = out[out.length - 1];
    last.args[4] = x2;
    last.args[5] = y2;
    return out;
  };
  const transformPathData = (segments, matrix) => segments.map(({code, args}) => {
    const moved = [];
    for (let index = 0; index + 1 < args.length; index += 2) {
      const x = args[index];
      const y = args[index + 1];
      moved.push(matrix.a * x + matrix.c * y + matrix.e, matrix.b * x + matrix.d * y + matrix.f);
    }
    return {
      code,
      args: moved
    };
  });
  const fitMatrix = (source, target) => {
    const chosen = Math.min(target.width / source.width, target.height / source.height);
    const scale = Number.isFinite(chosen) && chosen > 0 ? chosen : 1;
    return {
      a: scale,
      b: 0,
      c: 0,
      d: scale,
      e: target.x + target.width / 2 - (source.x + source.width / 2) * scale,
      f: target.y + target.height / 2 - (source.y + source.height / 2) * scale
    };
  };
  const printPathData = segments => segments.map(({code, args}) => {
    if (args.length === 0) return code;
    const numbers = args.map(value => {
      const rounded = Math.round(value * 100) / 100;
      return String(Object.is(rounded, -0) ? 0 : rounded);
    });
    return `${code} ${numbers.join(" ")}`;
  }).join(" ");
  const shapePathData = (tag, attrs) => {
    const number = (name, fallback = 0) => {
      const value = parseFloat(attrs[name]);
      return Number.isFinite(value) ? value : fallback;
    };
    if (tag === "path") {
      const d = typeof attrs.d === "string" ? attrs.d.trim() : "";
      return d === "" ? null : d;
    }
    if (tag === "rect") {
      const width = number("width");
      const height = number("height");
      if (!(width > 0) || !(height > 0)) return null;
      const x = number("x");
      const y = number("y");
      const declaredX = parseFloat(attrs.rx);
      const declaredY = parseFloat(attrs.ry);
      const rawX = Number.isFinite(declaredX) ? declaredX : declaredY;
      const rawY = Number.isFinite(declaredY) ? declaredY : declaredX;
      const rx = Math.min(Math.max(Number.isFinite(rawX) ? rawX : 0, 0), width / 2);
      const ry = Math.min(Math.max(Number.isFinite(rawY) ? rawY : 0, 0), height / 2);
      if (rx === 0 || ry === 0) {
        return `M ${x} ${y} H ${x + width} V ${y + height} H ${x} Z`;
      }
      return [`M ${x + rx} ${y}`, `H ${x + width - rx}`, `A ${rx} ${ry} 0 0 1 ${x + width} ${y + ry}`, `V ${y + height - ry}`, `A ${rx} ${ry} 0 0 1 ${x + width - rx} ${y + height}`, `H ${x + rx}`, `A ${rx} ${ry} 0 0 1 ${x} ${y + height - ry}`, `V ${y + ry}`, `A ${rx} ${ry} 0 0 1 ${x + rx} ${y}`, "Z"].join(" ");
    }
    if (tag === "circle" || tag === "ellipse") {
      const rx = tag === "circle" ? number("r") : number("rx");
      const ry = tag === "circle" ? number("r") : number("ry");
      if (!(rx > 0) || !(ry > 0)) return null;
      const cx = number("cx");
      const cy = number("cy");
      return [`M ${cx - rx} ${cy}`, `A ${rx} ${ry} 0 1 0 ${cx + rx} ${cy}`, `A ${rx} ${ry} 0 1 0 ${cx - rx} ${cy}`, "Z"].join(" ");
    }
    if (tag === "line") {
      const x1 = number("x1");
      const y1 = number("y1");
      const x2 = number("x2");
      const y2 = number("y2");
      if (x1 === x2 && y1 === y2) return null;
      return `M ${x1} ${y1} L ${x2} ${y2}`;
    }
    if (tag === "polyline" || tag === "polygon") {
      const values = String(attrs.points ?? "").trim().split(/[\s,]+/).map(Number).filter(value => Number.isFinite(value));
      if (values.length < 4) return null;
      const steps = [`M ${values[0]} ${values[1]}`];
      for (let index = 2; index + 1 < values.length; index += 2) {
        steps.push(`L ${values[index]} ${values[index + 1]}`);
      }
      if (tag === "polygon") steps.push("Z");
      return steps.join(" ");
    }
    return null;
  };
  const svgToPathData = (svgText, targetPathData, doc = document) => {
    const NS = "http://www.w3.org/2000/svg";
    const parsed = new DOMParser().parseFromString(String(svgText), "image/svg+xml");
    if (parsed.getElementsByTagName("parsererror").length > 0 || !parsed.documentElement || parsed.documentElement.localName !== "svg") {
      throw new Error("That file is not an SVG, or its markup is malformed.");
    }
    const host = doc.createElement("div");
    host.setAttribute("aria-hidden", "true");
    host.style.cssText = "position:fixed;left:-99999px;top:0;width:600px;height:600px;overflow:hidden;";
    const svg = doc.importNode(parsed.documentElement, true);
    host.appendChild(svg);
    doc.body.appendChild(host);
    try {
      const reference = doc.createElementNS(NS, "g");
      svg.appendChild(reference);
      const rootMatrix = reference.getScreenCTM();
      const defining = ["defs", "clipPath", "mask", "symbol", "marker", "pattern"];
      const isDefinition = element => {
        for (let node = element.parentNode; node && node !== svg; node = node.parentNode) {
          if (defining.includes(node.localName)) return true;
        }
        return false;
      };
      const shapes = [...svg.querySelectorAll("path,rect,circle,ellipse,line,polyline,polygon")];
      const segments = [];
      let shapesUsed = 0;
      let firstProblem = null;
      for (const element of shapes) {
        if (isDefinition(element)) continue;
        if (doc.defaultView.getComputedStyle(element).display === "none") continue;
        const attrs = {};
        for (const attribute of element.attributes) attrs[attribute.localName] = attribute.value;
        const d = shapePathData(element.localName, attrs);
        if (d === null) continue;
        let own;
        try {
          own = normalisePathData(parsePathData(d));
        } catch (error) {
          firstProblem = firstProblem ?? error.message;
          continue;
        }
        const matrix = element.getScreenCTM();
        segments.push(...rootMatrix && matrix ? transformPathData(own, rootMatrix.inverse().multiply(matrix)) : own);
        shapesUsed += 1;
      }
      if (segments.length === 0) {
        if (firstProblem) throw new Error(`This SVG has unreadable path data: ${firstProblem}.`);
        const untraceable = ["text", "image", "use"].find(tag => svg.getElementsByTagName(tag).length > 0);
        throw new Error(untraceable ? `This SVG draws with <${untraceable}>, which has no outline to trace. Convert it to paths and try again.` : "This SVG has no shapes to import.");
      }
      const probe = doc.createElementNS(NS, "path");
      svg.appendChild(probe);
      probe.setAttribute("d", printPathData(segments));
      const source = probe.getBBox();
      if (!(source.width > 0) || !(source.height > 0)) {
        if (!(source.width > 0) && !(source.height > 0)) {
          throw new Error("This SVG's shapes have no size.");
        }
      }
      probe.setAttribute("d", String(targetPathData));
      const target = probe.getBBox();
      return {
        d: printPathData(transformPathData(segments, fitMatrix(source, target))),
        shapes: shapesUsed
      };
    } finally {
      host.remove();
    }
  };
  const granularity = value => {
    const decimals = String(value).split(".")[1];
    return decimals ? Number(`1e-${decimals.length}`) : 1;
  };
  const readout = (variable, value) => {
    if (variable.type === "number") return "";
    if (variable.type === "color") return String(value);
    if (variable.type === "enum") {
      const hit = (variable.options ?? []).find(o => o.value === value);
      return hit ? hit.label ?? hit.value : String(value);
    }
    return "";
  };
  const control = (variable, value, onChange, note, onNote, onTyping) => {
    const options = variable.options ?? [];
    if (variable.type === "enum" && options.length > 0 && options.length <= 4) {
      return <div className="hf-ve-seg">
          {options.map(o => <button key={o.value} type="button" data-on={value === o.value} aria-pressed={value === o.value} onClick={() => onChange(o.value)} className="hf-ve-seg-btn hf-ve-tint">
              {o.label ?? o.value}
            </button>)}
        </div>;
    }
    if (variable.type === "enum") {
      return <select className="hf-ve-field hf-ve-select hf-ve-tint" value={value} aria-label={variable.label ?? variable.id} onChange={e => onChange(e.target.value)}>
          {options.map(o => <option key={o.value} value={o.value}>
              {o.label ?? o.value}
            </option>)}
        </select>;
    }
    if (variable.type === "number") {
      const min = Number(variable.min);
      const max = Number(variable.max);
      const unit = variable.unit ?? "";
      const declaredStep = Number(variable.step);
      const step = declaredStep > 0 ? declaredStep : 1;
      const label = variable.label ?? variable.id;
      if (!(Number.isFinite(min) && Number.isFinite(max) && max > min)) {
        return <input type="number" className="hf-ve-field hf-ve-mono hf-ve-tint" value={value} min={Number.isFinite(min) ? min : undefined} max={Number.isFinite(max) ? max : undefined} step={declaredStep > 0 ? declaredStep : granularity(variable.default)} aria-label={label} onChange={e => {
          const next = Number(e.target.value);
          if (e.target.value !== "" && Number.isFinite(next)) onChange(next);
        }} />;
      }
      const at = n => Math.min(1, Math.max(0, (Number(n) - min) / (max - min)));
      const now = at(value);
      const authored = at(variable.default);
      const place = fraction => ({
        offset: `${fraction * 100}%`,
        nudge: `${(0.5 - fraction) * 16}px`
      });
      const value_ = place(now);
      const default_ = place(authored);
      const grain = event => {
        event.currentTarget.step = event.shiftKey ? step / 10 : step;
      };
      return <div className="hf-ve-slider" style={{
        "--ve-fill": value_.offset,
        "--ve-fill-nudge": value_.nudge,
        "--ve-default": default_.offset,
        "--ve-default-nudge": default_.nudge
      }}>
          {}
          <div className="hf-ve-ruler" data-near={now < 0.14 ? "min" : now > 0.86 ? "max" : ""} aria-hidden="true">
            <span className="hf-ve-bound" data-end="min">
              {min}
            </span>
            <span className="hf-ve-bound" data-end="max">
              {max}
            </span>
            <span className="hf-ve-readout">
              {value}
              {unit}
            </span>
          </div>
          <span className="hf-ve-track">
            <input type="range" className="hf-ve-range" min={min} max={max} step={step} value={value} aria-label={label} aria-valuetext={`${value}${unit}`} onChange={e => onChange(Number(e.target.value))} onPointerDown={grain} onKeyDown={grain} onDoubleClick={() => onChange(variable.default)} />
            {}
            {Math.abs(now - authored) > 0.04 && <span className="hf-ve-default" aria-hidden="true" />}
          </span>
        </div>;
    }
    if (variable.type === "boolean") {
      const on = value === true || value === "true";
      return <button type="button" role="switch" aria-checked={on} aria-label={variable.label ?? variable.id} data-on={on} onClick={() => onChange(!on)} className="hf-ve-switch">
          <span className="hf-ve-switch-dot" />
        </button>;
    }
    if (variable.type === "color") {
      return <div className="flex items-center gap-2">
          <input type="color" className="hf-ve-swatch hf-ve-tint" value={value} aria-label={variable.label ?? variable.id} onChange={e => onChange(e.target.value)} />
          <input type="text" className="hf-ve-field hf-ve-mono hf-ve-tint" value={value} onChange={e => onChange(e.target.value)} onFocus={() => onTyping(variable.id)} onBlur={() => onTyping(null)} onKeyDown={e => {
        if (e.key === "Enter") e.currentTarget.blur();
      }} />
        </div>;
    }
    if (isSvgPathData(variable.default)) {
      const fileId = `hf-ve-file-${variable.id}`;
      const noteId = `hf-ve-note-${variable.id}`;
      const receive = file => {
        if (!file) return;
        file.text().then(text => {
          const {d, shapes} = svgToPathData(text, variable.default);
          onChange(d);
          onNote({
            tone: "ok",
            message: `${file.name}: ${shapes} shape${shapes === 1 ? "" : "s"} scaled to fit.`
          });
        }).catch(error => onNote({
          tone: "error",
          message: error.message
        }));
      };
      return <div className="hf-ve-drop" onDragOver={event => {
        event.preventDefault();
        event.currentTarget.dataset.over = "true";
      }} onDragLeave={event => {
        event.currentTarget.dataset.over = "false";
      }} onDrop={event => {
        event.preventDefault();
        event.currentTarget.dataset.over = "false";
        receive(event.dataTransfer.files[0]);
      }}>
          {}
          <div className="hf-ve-dropzone">
            <button type="button" className="hf-ve-btn hf-ve-tint" onClick={() => document.getElementById(fileId).click()}>
              Import SVG
            </button>
            <input id={fileId} type="file" accept=".svg,image/svg+xml" className="hf-ve-file" tabIndex={-1} aria-hidden="true" onChange={event => {
        receive(event.target.files[0]);
        event.target.value = "";
      }} />
            {}
            <p id={noteId} role="status" className="hf-ve-note" data-tone={note ? note.tone : ""}>
              {note ? note.message : "Or drop one here. Scaled to fit and centred."}
            </p>
          </div>
          <details className="hf-ve-advanced">
            <summary>Path data</summary>
            <input type="text" className="hf-ve-field hf-ve-mono hf-ve-tint" value={value} aria-label={variable.label ?? variable.id} onChange={e => onChange(e.target.value)} onFocus={() => onTyping(variable.id)} onBlur={() => onTyping(null)} onKeyDown={e => {
        if (e.key === "Enter") e.currentTarget.blur();
      }} />
          </details>
        </div>;
    }
    return <input type="text" className="hf-ve-field hf-ve-tint" value={value} aria-label={variable.label ?? variable.id} onChange={e => onChange(e.target.value)} onFocus={() => onTyping(variable.id)} onBlur={() => onTyping(null)} onKeyDown={e => {
      if (e.key === "Enter") e.currentTarget.blur();
    }} />;
  };
  const variablesKey = JSON.stringify(variables);
  const defaults = useMemo(() => {
    const built = {};
    for (const v of variables) if (v.default !== undefined) built[v.id] = v.default;
    return built;
  }, [variablesKey]);
  const urlKey = `vars-${compositionId}`;
  const readFromUrl = () => {
    if (typeof window === "undefined") return {};
    try {
      const raw = new URLSearchParams(window.location.search).get(urlKey);
      if (!raw) return {};
      const parsed = JSON.parse(raw);
      if (!parsed || typeof parsed !== "object" || Array.isArray(parsed)) return {};
      const declared = new Set(variables.map(v => v.id));
      return Object.fromEntries(Object.entries(parsed).filter(([id]) => declared.has(id)));
    } catch {
      return {};
    }
  };
  const [values, setValues] = useState(() => ({
    ...defaults,
    ...readFromUrl()
  }));
  useEffect(() => {
    const fromUrl = readFromUrl();
    if (Object.keys(fromUrl).length > 0) setValues(current => ({
      ...current,
      ...fromUrl
    }));
  }, []);
  useEffect(() => {
    if (typeof window === "undefined") return;
    const changed = Object.fromEntries(Object.entries(values).filter(([id, value]) => JSON.stringify(value) !== JSON.stringify(defaults[id])));
    const url = new URL(window.location.href);
    if (Object.keys(changed).length === 0) url.searchParams.delete(urlKey); else url.searchParams.set(urlKey, JSON.stringify(changed));
    const next = url.toString();
    if (next !== window.location.href) {
      window.history.replaceState(null, "", next);
      window.dispatchEvent(new CustomEvent("hf-vars-changed"));
    }
  }, [values, defaults, urlKey]);
  const [notes, setNotes] = useState({});
  const [typing, setTyping] = useState(null);
  const posted = useRef(null);
  const [tab, setTab] = useState("preview");
  const frame = useRef(null);
  const bootstrap = ["<!doctype html><html><head><meta charset='utf-8'>", "<style>html,body{margin:0;height:100%;overflow:hidden;background:transparent}", "hyperframes-player{display:block;width:100%;height:100%}</style>", '<script src="https://cdn.jsdelivr.net/npm/@hyperframes/player@0.7/dist/hyperframes-player.global.js"></' + "script>", "</head><body><script>", "(function(){", `  var PAYLOAD = ${JSON.stringify(previewSrc)};`, `  var INITIAL = ${JSON.stringify({
    ...defaults,
    ...readFromUrl()
  })};`, "  var html = null, player = null, poll = null;", "  function withValues(source, values) {", "    var json = JSON.stringify(values);", "    var attr = json.replace(/'/g, '&#39;');", "    var out = source.replace(/\\sdata-variable-values=(?:\"[^\"]*\"|'[^']*')/gi, '');", "    out = out.replace(/(data-composition-src=)/gi, \"data-variable-values='\" + attr + \"' $1\");", "    var tag = '<' + 'script>window.__hfVariables=' + json + ';<' + '/script>';", "    return /<head[^>]*>/i.test(out)", "      ? out.replace(/<head([^>]*)>/i, '<head$1>' + tag)", "      : tag + out;", "  }", "  function arm(resumeAt) {", "    clearInterval(poll);", "    var last = -1, tries = 0, seeked = false;", "    poll = setInterval(function () {", "      if (player.ready) {", "        if (!seeked) { seeked = true; if (resumeAt > 0) player.seek(resumeAt); }", "        player.play();", "      }", "      if (seeked && player.currentTime > 0 && player.currentTime !== last) {", "        clearInterval(poll); return;", "      }", "      last = player.currentTime;", "      if (++tries > 150) clearInterval(poll);", "    }, 100);", "  }", "  function mount(values, resumeAt) {", "    if (html === null) return;", "    player.setAttribute('srcdoc', withValues(html, values));", "    arm(resumeAt || 0);", "  }", "  player = document.createElement('hyperframes-player');", "  player.setAttribute('controls', ''); player.setAttribute('muted', '');", "  document.body.appendChild(player);", "  player.addEventListener('ended', function () { player.seek(0); player.play(); });", "  fetch(PAYLOAD).then(function (r) { return r.json(); }).then(function (d) {", "    html = d.html; mount(INITIAL, 0);", "  }).catch(function (e) {", "    document.body.innerHTML = '<pre style=\"color:#f66;font:12px monospace;padding:12px\">preview unavailable: ' + e + '</pre>';", "  });", "  addEventListener('message', function (event) {", "    var values = event.data && event.data.hfVariables;", "    if (!values) return;", "    mount(values, player.currentTime || 0);", "  });", "})();", "</" + "script></body></html>"].join("");
  useEffect(() => {
    if (typing !== null) return;
    const payload = JSON.stringify(values);
    if (payload === posted.current) return;
    const timer = setTimeout(() => {
      const target = frame.current && frame.current.contentWindow;
      if (!target) return;
      posted.current = payload;
      target.postMessage({
        hfVariables: values
      }, window.location.origin);
    }, 150);
    return () => clearTimeout(timer);
  }, [values, typing]);
  const printed = JSON.stringify(values, null, 2).split("\n").join("\n  ");
  const attributes = [["data-composition-id", `"${compositionId}"`], ["data-composition-src", `"${compositionSrc}"`], ["data-variable-values", `'${printed}'`]];
  const snippetLines = [[[SHIKI.punct, "<"], [SHIKI.tag, "div"]]];
  for (const [name, literal] of attributes) {
    const [head, ...rest] = literal.split("\n");
    snippetLines.push([[SHIKI.attr, `  ${name}`], [SHIKI.equals, "="], [SHIKI.value, head]]);
    for (const line of rest) snippetLines.push([[SHIKI.value, line]]);
  }
  snippetLines.push([[SHIKI.punct, "></"], [SHIKI.tag, "div"], [SHIKI.punct, ">"]]);
  const dirty = variables.some(v => values[v.id] !== defaults[v.id]);
  const installCommand = (() => {
    const base = `npx hyperframes add ${compositionId}`;
    if (!dirty) return base;
    const changed = {};
    for (const v of variables) {
      if (JSON.stringify(values[v.id]) !== JSON.stringify(defaults[v.id])) changed[v.id] = values[v.id];
    }
    return `${base} --vars '${JSON.stringify(changed)}'`;
  })();
  const TABS = [["preview", "Preview"], ...children ? [["code", "Code"]] : [], ["snippet", "Snippet"]];
  return <div className="hf-ve not-prose my-4">
      <style dangerouslySetInnerHTML={{
    __html: CSS
  }} />

      <div className="mb-3 flex items-center gap-3">
        <div className="hf-ve-tabs">
          {TABS.map(([id, label]) => <button key={id} type="button" data-on={tab === id} aria-pressed={tab === id} onClick={() => setTab(id)} className="hf-ve-tab hf-ve-tint">
              {label}
            </button>)}
        </div>
      </div>

      {}
      <div className="hf-ve-frame">
        <div className="hf-ve-cell" data-on={tab === "preview"}>
          <iframe ref={frame} srcDoc={bootstrap} className="hf-ve-preview block aspect-video w-full" title={`${compositionId} preview`} />
        </div>
        {children && <div className="hf-ve-cell" data-on={tab === "code"}>
            {children}
          </div>}
        <div className="hf-ve-cell hf-ve-snippet" data-on={tab === "snippet"}>
          {}
          <CodeBlock filename="Terminal">
            <pre className="shiki shiki-themes github-light-default dark-plus" style={{
    backgroundColor: "rgb(255, 255, 255)",
    "--shiki-dark-bg": "#0B0C0E",
    color: "rgb(31, 35, 40)",
    "--shiki-dark": "#D4D4D4"
  }}>
              <code>
                <span className="line">
                  <span style={SHIKI.value}>{installCommand}</span>
                  {"\n"}
                </span>
              </code>
            </pre>
          </CodeBlock>
          {}
          <CodeBlock filename="index.html">
            <pre className="shiki shiki-themes github-light-default dark-plus" style={{
    backgroundColor: "rgb(255, 255, 255)",
    "--shiki-dark-bg": "#0B0C0E",
    color: "rgb(31, 35, 40)",
    "--shiki-dark": "#D4D4D4"
  }}>
              <code>
                {snippetLines.map((tokens, line) => <span key={line} className="line">
                    {tokens.map(([style, text], token) => <span key={token} style={style}>
                        {text}
                      </span>)}
                    {"\n"}
                  </span>)}
              </code>
            </pre>
          </CodeBlock>
        </div>
      </div>

      <div className="hf-ve-panel">
        <div className="hf-ve-head">
          <span className="hf-ve-title">Customize</span>
          <button type="button" onClick={() => {
    setValues(defaults);
    setNotes({});
  }} disabled={!dirty} className="hf-ve-btn hf-ve-tint">
            Reset
          </button>
        </div>
        <div className="hf-ve-grid">
          {variables.map(v => <div key={v.id}>
              <div className="hf-ve-row">
                <label className="hf-ve-label">{v.label ?? v.id}</label>
                <span className="hf-ve-value">{readout(v, values[v.id])}</span>
              </div>
              {control(v, values[v.id], next => setValues(prev => ({
    ...prev,
    [v.id]: next
  })), notes[v.id], note => setNotes(prev => ({
    ...prev,
    [v.id]: note
  })), setTyping)}
              {v.description && <p className="hf-ve-desc">{v.description}</p>}
            </div>)}
        </div>
      </div>
    </div>;
};

export const InstallCommand = ({command, item}) => {
  const [copied, setCopied] = React.useState(false);
  const [tuned, setTuned] = React.useState("");
  React.useEffect(() => {
    if (!item) return;
    const read = () => {
      try {
        const raw = new URLSearchParams(window.location.search).get(`vars-${item}`);
        if (!raw) return setTuned("");
        const parsed = JSON.parse(raw);
        if (!parsed || typeof parsed !== "object" || Array.isArray(parsed)) return setTuned("");
        if (Object.keys(parsed).length === 0) return setTuned("");
        setTuned(` --vars '${JSON.stringify(parsed)}'`);
      } catch {
        setTuned("");
      }
    };
    read();
    window.addEventListener("hf-vars-changed", read);
    window.addEventListener("popstate", read);
    return () => {
      window.removeEventListener("hf-vars-changed", read);
      window.removeEventListener("popstate", read);
    };
  }, [item]);
  const fullCommand = `${command}${tuned}`;
  const copy = async () => {
    try {
      if (navigator.clipboard && window.isSecureContext) {
        await navigator.clipboard.writeText(fullCommand);
      } else {
        const previous = document.activeElement;
        const scratch = document.createElement("textarea");
        scratch.value = fullCommand;
        scratch.setAttribute("readonly", "");
        scratch.style.position = "fixed";
        scratch.style.opacity = "0";
        document.body.appendChild(scratch);
        scratch.select();
        document.execCommand("copy");
        document.body.removeChild(scratch);
        previous?.focus?.();
      }
      setCopied(true);
      setTimeout(() => setCopied(false), 2000);
    } catch {}
  };
  return <div className="hf-install-command not-prose my-4 flex items-stretch overflow-hidden rounded-xl border border-zinc-200 bg-zinc-50 dark:border-zinc-800 dark:bg-zinc-900">
      <code className="flex-1 overflow-x-auto whitespace-nowrap border-r border-zinc-200 px-4 py-3 font-mono text-sm text-zinc-800 dark:border-zinc-800 dark:text-zinc-100">
        {fullCommand}
      </code>
      <button type="button" onClick={copy} data-copied={copied ? "true" : "false"} aria-label={`Copy ${command} to the clipboard`} className="hf-install-copy">
        <svg className="hf-install-copy-clipboard" xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 18 18" fill="none" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round" aria-hidden="true">
          <path d="M14.25 5.25H7.25C6.14543 5.25 5.25 6.14543 5.25 7.25V14.25C5.25 15.3546 6.14543 16.25 7.25 16.25H14.25C15.3546 16.25 16.25 15.3546 16.25 14.25V7.25C16.25 6.14543 15.3546 5.25 14.25 5.25Z" />
          <path d="M2.80103 11.998L1.77203 5.07397C1.61003 3.98097 2.36403 2.96397 3.45603 2.80197L10.38 1.77297C11.313 1.63397 12.19 2.16297 12.528 3.00097" />
        </svg>
        <svg className="hf-install-copy-check" xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 18 18" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round" aria-hidden="true">
          <path d="M2.75 9.5L6.5 13.25L15.25 4.5" />
        </svg>
      </button>
      <span className="hf-install-copy-status" role="status" aria-live="polite">
        {copied ? "Copied" : ""}
      </span>
    </div>;
};

<VariablesExplorer previewSrc="/public/catalog/components/caption-camera-follow.json" compositionId="caption-camera-follow" compositionSrc="compositions/components/caption-camera-follow.html" variables={[{"id":"accent","type":"enum","role":"style","label":"Accent","description":"Colour of the highlighted words. gold is the original.","default":"gold","options":[{"value":"gold","label":"Gold"},{"value":"green","label":"Green"},{"value":"blue","label":"Blue"},{"value":"violet","label":"Violet"}]},{"id":"framing","type":"enum","role":"style","label":"Framing","description":"Air the camera leaves around the written block, so the words land larger or smaller in frame.","default":"standard","options":[{"value":"tight","label":"Tight"},{"value":"standard","label":"Standard"},{"value":"wide","label":"Wide"}]},{"id":"smear","type":"enum","role":"style","label":"Smear","description":"Scales the radial motion blur each camera move carries, from none to a heavy streak.","default":"standard","options":[{"value":"off","label":"Off"},{"value":"subtle","label":"Subtle"},{"value":"standard","label":"Standard"},{"value":"heavy","label":"Heavy"}]}]}>
  ```html caption-camera-follow.html theme={null}
  <!doctype html>
  <!--
    caption-camera-follow: the words do not move, the camera does.

    One sentence. Layout is self similar: every new word is sized as a fraction of the
    bounding box of everything written so far, and is dropped either to the right of that
    box or onto a new line below it, alternating. Because each word is measured against a
    box that keeps growing, the box grows geometrically, so the camera pulls back at a
    steady exponential rate and every word arrives at roughly the same size on screen. Old
    words stay lit and simply become small, piling up toward the top left the way
    handwriting fills a page. The last beat carries the same pull back all the way out
    until the whole sentence is readable at once.

    Variables. The script reads each one, falls back to the declared default on
    anything missing or unrecognised, and applies it before the timeline is built.
    Duration, word order and cadence are untouched by them.

      - accent (gold | green | blue | violet, default gold): the colour of the
        highlighted words.
      - framing (tight | standard | wide, default standard): the air the camera
        leaves around the written block. tight lands each word larger in frame,
        wide sits further back. Every move and the closing pull back scale
        together, so the shot stays one continuous camera.
      - smear (off | subtle | standard | heavy, default standard): scales the
        radial motion blur each move carries. off renders every frame sharp.

    On every default the result is identical to the original: gold highlights, a
    1.36 margin around the block and a peak smear of 2.6 percent of frame width.

    Every ease is a cubic bezier written out by hand and solved in this file. No preset is
    used anywhere. Motion blur is radial, the way it reads in real camera footage: each word
    carries its own blur share, scaled by how far that word sits from the centre of the move,
    so the frame smears outward from the point the camera is pushing toward. One shared
    amount variable is tweened per move and every word multiplies it by its own distance
    share, so the whole radial pulse costs one tween instead of fourteen.

    Mount contract: everything lives inside <template>, styles and scripts included, and the
    scripts sit INSIDE the composition root. A host clones template content into its own
    mount and only runs scripts found inside the root; markup left outside is copied without
    its behaviour, which renders a black card with no timeline at all.
  -->
  <html lang="en">
    <head>
      <meta charset="UTF-8" />
      <title>Camera Follow Captions</title>
    </head>
    <body>
      <template>
        <div
          id="root"
          class="clip cf-root"
          data-composition-id="caption-camera-follow"
          data-duration="9"
          data-fps="30"
          data-composition-variables='[
            { "id": "accent", "type": "enum", "role": "style", "label": "Accent", "description": "Colour of the highlighted words. gold is the original.", "default": "gold", "options": [{ "value": "gold", "label": "Gold" }, { "value": "green", "label": "Green" }, { "value": "blue", "label": "Blue" }, { "value": "violet", "label": "Violet" }] },
            { "id": "framing", "type": "enum", "role": "style", "label": "Framing", "description": "Air the camera leaves around the written block, so the words land larger or smaller in frame.", "default": "standard", "options": [{ "value": "tight", "label": "Tight" }, { "value": "standard", "label": "Standard" }, { "value": "wide", "label": "Wide" }] },
            { "id": "smear", "type": "enum", "role": "style", "label": "Smear", "description": "Scales the radial motion blur each camera move carries, from none to a heavy streak.", "default": "standard", "options": [{ "value": "off", "label": "Off" }, { "value": "subtle", "label": "Subtle" }, { "value": "standard", "label": "Standard" }, { "value": "heavy", "label": "Heavy" }] }
          ]'
        >
          <style>
            [data-composition-id="caption-camera-follow"] {
              --cf-accent: #ffd84d;
              --ink: #ffffff;
              position: absolute;
              inset: 0;
              overflow: hidden;
              background: transparent;
              pointer-events: none;
            }
            #cf-stage {
              position: absolute;
              inset: 0;
              overflow: hidden;
            }
            #cf-world {
              position: absolute;
              left: 0;
              top: 0;
              width: 0;
              height: 0;
              --amt: 0px;
            }
            .cf-word {
              position: absolute;
              white-space: nowrap;
              font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
              font-weight: 700;
              text-transform: uppercase;
              letter-spacing: 0.005em;
              line-height: 0.78;
              color: var(--ink);
              opacity: 0;
              --k: 0;
              filter: blur(calc(var(--k) * var(--amt)));
            }
            .cf-word.is-accent {
              color: var(--cf-accent);
            }
            #cf-vignette {
              position: absolute;
              inset: 0;
              background: radial-gradient(
                ellipse at 50% 50%,
                rgba(0, 0, 0, 0) 42%,
                rgba(0, 0, 0, 0.55) 100%
              );
            }
          </style>

          <div id="cf-stage">
            <div id="cf-world"></div>
          </div>
          <div id="cf-vignette"></div>

          <script src="https://cdn.jsdelivr.net/npm/gsap@3.14.2/dist/gsap.min.js"></script>
          <script>
            (function () {
              gsap.defaults({ immediateRender: false });

              /* Cubic bezier solver. Newton first, bisection as the fallback, so it is
                 exact and deterministic for every input. */
              function bezier(x1, y1, x2, y2) {
                function curve(t, a1, a2) {
                  var A = 1 - 3 * a2 + 3 * a1;
                  var B = 3 * a2 - 6 * a1;
                  var C = 3 * a1;
                  return ((A * t + B) * t + C) * t;
                }
                function slope(t, a1, a2) {
                  var A = 1 - 3 * a2 + 3 * a1;
                  var B = 3 * a2 - 6 * a1;
                  var C = 3 * a1;
                  return (3 * A * t + 2 * B) * t + C;
                }
                return function (p) {
                  if (p <= 0) return 0;
                  if (p >= 1) return 1;
                  var t = p;
                  for (var i = 0; i < 8; i++) {
                    var d = slope(t, x1, x2);
                    if (Math.abs(d) < 1e-6) break;
                    var e = curve(t, x1, x2) - p;
                    if (Math.abs(e) < 1e-7) return curve(t, y1, y2);
                    t -= e / d;
                  }
                  var lo = 0;
                  var hi = 1;
                  t = p;
                  for (var j = 0; j < 24; j++) {
                    var x = curve(t, x1, x2);
                    if (Math.abs(x - p) < 1e-7) break;
                    if (x > p) hi = t;
                    else lo = t;
                    t = (lo + hi) / 2;
                  }
                  return curve(t, y1, y2);
                };
              }

              /* Leaves the mark fast, spends most of its time arriving. */
              var EASE_STEP = bezier(0.31, 0, 0.11, 1);
              /* The closing pull back: slower to leave, glides a long way out. */
              var EASE_WIDE = bezier(0.42, 0, 0.14, 1);
              /* Word ink coming up. */
              var EASE_INK = bezier(0.2, 0.7, 0.3, 1);
              /* Blur rising into the move and wiped off out of it. */
              var EASE_BLUR_UP = bezier(0.2, 0.8, 0.4, 1);
              var EASE_BLUR_DOWN = bezier(0.5, 0, 0.2, 1);

              var vars =
                window.__hyperframes && window.__hyperframes.getVariables
                  ? window.__hyperframes.getVariables()
                  : {};

              /* Unrecognised overrides return to their declared defaults. */
              function pick(table, value, fallback) {
                return Object.prototype.hasOwnProperty.call(table, value) ? value : fallback;
              }

              var ACCENTS = {
                gold: "#ffd84d",
                green: "#34d399",
                blue: "#38bdf8",
                violet: "#a78bfa",
              };
              /* Framing scales the margin every camera pose is fitted with, so one
                 number moves the whole shot in or out without touching cadence. */
              var FRAMINGS = { tight: 0.82, standard: 1, wide: 1.25 };
              var SMEARS = { off: 0, subtle: 0.5, standard: 1, heavy: 1.9 };

              var ACCENT = ACCENTS[pick(ACCENTS, vars.accent, "gold")];
              var FRAMING = FRAMINGS[pick(FRAMINGS, vars.framing, "standard")];
              var SMEAR = SMEARS[pick(SMEARS, vars.smear, "standard")];

              var DUR = 9;
              var STEP = 0.52;
              var MOVE = 0.4;

              var WORDS = [
                { text: "write" },
                { text: "the" },
                { text: "html", accent: true },
                { text: "and" },
                { text: "the" },
                { text: "video", accent: true },
                { text: "renders" },
                { text: "itself" },
                { text: "no" },
                { text: "timeline" },
                { text: "no" },
                { text: "keyframes", accent: true },
                { text: "just" },
                { text: "code", accent: true },
              ];

              var world = document.getElementById("cf-world");
              var stage = document.getElementById("cf-stage");
              /* The runtime strips the root id on clone, so reach the root through a
                 descendant instead of getElementById. */
              var root = stage.parentElement;
              var FRAME_W = root.clientWidth || 1080;
              var FRAME_H = root.clientHeight || 1920;
              root.style.setProperty("--cf-accent", ACCENT);

              /* Base size is picked so the opening shot sits near 1:1. Everything after it
                 is a pull back, so the world is only ever scaled down and type stays crisp. */
              var BASE = Math.max(FRAME_W, FRAME_H) * 0.16;
              /* Each new word is this fraction of the current box height. */
              var RATIO = 0.72;
              var MARGIN = 1.36 * FRAMING;

              var ruler = document.createElement("div");
              ruler.style.cssText =
                "position:absolute;left:-99999px;top:0;white-space:nowrap;visibility:hidden;" +
                'font-family:"Helvetica Neue",Helvetica,Arial,sans-serif;font-weight:700;' +
                "text-transform:uppercase;letter-spacing:0.005em;line-height:0.78";
              world.appendChild(ruler);

              var box = null;
              WORDS.forEach(function (wd, i) {
                var fs = i === 0 ? BASE : (box.y1 - box.y0) * RATIO;
                ruler.style.fontSize = fs + "px";
                ruler.textContent = wd.text;
                var w = ruler.getBoundingClientRect().width;
                var h = fs * 0.78;
                var gap = fs * 0.07;

                var x, y;
                if (i === 0) {
                  x = 0;
                  y = 0;
                } else if ((box.x1 - box.x0) / (box.y1 - box.y0) < FRAME_W / FRAME_H) {
                  /* block is narrower than the frame, so grow sideways: to the right of
                     everything, sitting on the same baseline */
                  x = box.x1 + gap;
                  y = box.y1 - h;
                } else {
                  /* block is already wide enough, so grow downward: onto a new line under
                     everything, left edges aligned */
                  x = box.x0;
                  y = box.y1 + gap;
                }

                wd.fs = fs;
                wd.x = x;
                wd.y = y;

                box = box
                  ? {
                      x0: Math.min(box.x0, x),
                      y0: Math.min(box.y0, y),
                      x1: Math.max(box.x1, x + w),
                      y1: Math.max(box.y1, y + h),
                    }
                  : { x0: x, y0: y, x1: x + w, y1: y + h };
                wd.box = { x0: box.x0, y0: box.y0, x1: box.x1, y1: box.y1 };
              });
              world.removeChild(ruler);

              var FULL = box;

              function poseFor(b, margin) {
                var bw = (b.x1 - b.x0) * margin;
                var bh = (b.y1 - b.y0) * margin;
                var s = Math.min(FRAME_W / bw, FRAME_H / bh);
                return {
                  x: FRAME_W / 2 - (s * (b.x0 + b.x1)) / 2,
                  y: FRAME_H / 2 - (s * (b.y0 + b.y1)) / 2,
                  scale: s,
                };
              }

              var els = WORDS.map(function (wd) {
                var el = document.createElement("div");
                el.className = "cf-word" + (wd.accent ? " is-accent" : "");
                el.textContent = wd.text;
                el.style.left = wd.x + "px";
                el.style.top = wd.y + "px";
                el.style.fontSize = wd.fs + "px";
                world.appendChild(el);
                return el;
              });

              /* Re-derive every framing box from what the browser actually laid out, so
                 the camera is fitted to real ink and never to arithmetic that drifted. */
              var run = null;
              els.forEach(function (el, i) {
                var r = {
                  x0: el.offsetLeft,
                  y0: el.offsetTop,
                  x1: el.offsetLeft + el.offsetWidth,
                  y1: el.offsetTop + el.offsetHeight,
                };
                run = run
                  ? {
                      x0: Math.min(run.x0, r.x0),
                      y0: Math.min(run.y0, r.y0),
                      x1: Math.max(run.x1, r.x1),
                      y1: Math.max(run.y1, r.y1),
                    }
                  : r;
                WORDS[i].box = { x0: run.x0, y0: run.y0, x1: run.x1, y1: run.y1 };
              });
              FULL = run;

              /* Rest state is pinned outside the timeline. */
              var first = poseFor(WORDS[0].box, MARGIN);
              gsap.set(world, {
                transformOrigin: "0 0",
                x: first.x,
                y: first.y,
                scale: first.scale,
              });
              gsap.set(els, { opacity: 0, "--k": 0 });
              gsap.set(world, { "--amt": "0px" });
              /* The first word is already on the page when the shot opens, so frame zero
                 is never empty. */
              gsap.set(els[0], { opacity: 1 });

              var tl = gsap.timeline({ paused: true });
              /* Peak smear at the rim of the frame, in screen pixels. */
              var BLUR = FRAME_W * 0.026 * SMEAR;
              var HALF_DIAG = Math.sqrt(FRAME_W * FRAME_W + FRAME_H * FRAME_H) / 2;

              /* Radial blur, the way a real zoom smears: a point far from the centre of
                 the move sweeps across more of the frame than one sitting on it, so it
                 streaks more. Each word gets its own share, --k, of one shared amount,
                 --amt, which is the only thing that animates. The share is fixed for the
                 length of a move and set with the camera, so this stays one tween per
                 move rather than one per word per move. --amt is authored in world units,
                 because a filter on a scaled child is applied before the scale, so the
                 screen blur has to be divided back out by the camera scale. */
              function smear(centre, scale, count, at, up, down, peak) {
                for (var j = 0; j < count; j++) {
                  var el = els[j];
                  var cx = el.offsetLeft + el.offsetWidth / 2;
                  var cy = el.offsetTop + el.offsetHeight / 2;
                  var d =
                    (scale *
                      Math.sqrt(
                        (cx - centre.x) * (cx - centre.x) + (cy - centre.y) * (cy - centre.y),
                      )) /
                    HALF_DIAG;
                  tl.set(el, { "--k": (0.2 + 1.15 * Math.min(1, d)).toFixed(3) }, at);
                }
                var amt = peak / scale;
                tl.fromTo(
                  world,
                  { "--amt": "0px" },
                  { "--amt": amt + "px", duration: up, ease: EASE_BLUR_UP },
                  at,
                );
                tl.to(world, { "--amt": "0px", duration: down, ease: EASE_BLUR_DOWN }, at + up);
              }

              WORDS.forEach(function (wd, i) {
                var t = i * STEP;
                if (i === 0) return;

                tl.fromTo(els[i], { opacity: 0 }, { opacity: 1, duration: 0.16, ease: EASE_INK }, t);

                var p = poseFor(wd.box, MARGIN);
                tl.to(world, { x: p.x, y: p.y, scale: p.scale, duration: MOVE, ease: EASE_STEP }, t);

                smear(
                  { x: (wd.box.x0 + wd.box.x1) / 2, y: (wd.box.y0 + wd.box.y1) / 2 },
                  p.scale,
                  i + 1,
                  t,
                  MOVE * 0.24,
                  MOVE * 0.44,
                  BLUR,
                );
              });

              /* The resolve: the same pull back, carried all the way out. */
              var wide = poseFor(FULL, 1.2 * FRAMING);
              var wideAt = (WORDS.length - 1) * STEP + 0.62;
              tl.to(
                world,
                {
                  x: wide.x,
                  y: wide.y,
                  scale: wide.scale,
                  duration: 0.94,
                  ease: EASE_WIDE,
                },
                wideAt,
              );
              smear(
                { x: (FULL.x0 + FULL.x1) / 2, y: (FULL.y0 + FULL.y1) / 2 },
                wide.scale,
                els.length,
                wideAt,
                0.3,
                0.58,
                BLUR * 0.8,
              );

              tl.set({}, {}, DUR);
              tl.seek(0);

              window.__timelines = window.__timelines || {};
              window.__timelines["caption-camera-follow"] = tl;
            })();
          </script>
        </div>
      </template>
    </body>
  </html>
  ```
</VariablesExplorer>

## Install

<InstallCommand command="npx hyperframes add caption-camera-follow" item="caption-camera-follow" />

That writes one file: `compositions/components/caption-camera-follow.html`.

## Paste it into your composition

Open `compositions/components/caption-camera-follow.html` and copy what is inside into your own composition.

A component has no size or duration of its own. It takes both from the composition
you paste it into.

## Variables

Every one of these has a default, so the piece works untouched. Set the ones you
want to change on the element:

| Variable  | Default    | Accepts                              | What it does                                                                                  |
| --------- | ---------- | ------------------------------------ | --------------------------------------------------------------------------------------------- |
| `accent`  | `gold`     | `gold`, `green`, `blue`, `violet`    | Colour of the highlighted words. gold is the original.                                        |
| `framing` | `standard` | `tight`, `standard`, `wide`          | Air the camera leaves around the written block, so the words land larger or smaller in frame. |
| `smear`   | `standard` | `off`, `subtle`, `standard`, `heavy` | Scales the radial motion blur each camera move carries, from none to a heavy streak.          |

Set them with `data-variable-values` on the element that mounts it. These are the
defaults, so this behaves exactly like the preview above until you change one:

```html wrap theme={null}
<div
  data-composition-id="caption-camera-follow"
  data-composition-src="compositions/components/caption-camera-follow.html"
  data-variable-values='{"accent":"gold","framing":"standard","smear":"standard"}'
></div>
```

## Source

<Accordion title={`caption-camera-follow.html`}>
  ```html theme={null}
  <!doctype html>
  <!--
    caption-camera-follow: the words do not move, the camera does.

    One sentence. Layout is self similar: every new word is sized as a fraction of the
    bounding box of everything written so far, and is dropped either to the right of that
    box or onto a new line below it, alternating. Because each word is measured against a
    box that keeps growing, the box grows geometrically, so the camera pulls back at a
    steady exponential rate and every word arrives at roughly the same size on screen. Old
    words stay lit and simply become small, piling up toward the top left the way
    handwriting fills a page. The last beat carries the same pull back all the way out
    until the whole sentence is readable at once.

    Variables. The script reads each one, falls back to the declared default on
    anything missing or unrecognised, and applies it before the timeline is built.
    Duration, word order and cadence are untouched by them.

      - accent (gold | green | blue | violet, default gold): the colour of the
        highlighted words.
      - framing (tight | standard | wide, default standard): the air the camera
        leaves around the written block. tight lands each word larger in frame,
        wide sits further back. Every move and the closing pull back scale
        together, so the shot stays one continuous camera.
      - smear (off | subtle | standard | heavy, default standard): scales the
        radial motion blur each move carries. off renders every frame sharp.

    On every default the result is identical to the original: gold highlights, a
    1.36 margin around the block and a peak smear of 2.6 percent of frame width.

    Every ease is a cubic bezier written out by hand and solved in this file. No preset is
    used anywhere. Motion blur is radial, the way it reads in real camera footage: each word
    carries its own blur share, scaled by how far that word sits from the centre of the move,
    so the frame smears outward from the point the camera is pushing toward. One shared
    amount variable is tweened per move and every word multiplies it by its own distance
    share, so the whole radial pulse costs one tween instead of fourteen.

    Mount contract: everything lives inside <template>, styles and scripts included, and the
    scripts sit INSIDE the composition root. A host clones template content into its own
    mount and only runs scripts found inside the root; markup left outside is copied without
    its behaviour, which renders a black card with no timeline at all.
  -->
  <html lang="en">
    <head>
      <meta charset="UTF-8" />
      <title>Camera Follow Captions</title>
    </head>
    <body>
      <template>
        <div
          id="root"
          class="clip cf-root"
          data-composition-id="caption-camera-follow"
          data-duration="9"
          data-fps="30"
          data-composition-variables='[
            { "id": "accent", "type": "enum", "role": "style", "label": "Accent", "description": "Colour of the highlighted words. gold is the original.", "default": "gold", "options": [{ "value": "gold", "label": "Gold" }, { "value": "green", "label": "Green" }, { "value": "blue", "label": "Blue" }, { "value": "violet", "label": "Violet" }] },
            { "id": "framing", "type": "enum", "role": "style", "label": "Framing", "description": "Air the camera leaves around the written block, so the words land larger or smaller in frame.", "default": "standard", "options": [{ "value": "tight", "label": "Tight" }, { "value": "standard", "label": "Standard" }, { "value": "wide", "label": "Wide" }] },
            { "id": "smear", "type": "enum", "role": "style", "label": "Smear", "description": "Scales the radial motion blur each camera move carries, from none to a heavy streak.", "default": "standard", "options": [{ "value": "off", "label": "Off" }, { "value": "subtle", "label": "Subtle" }, { "value": "standard", "label": "Standard" }, { "value": "heavy", "label": "Heavy" }] }
          ]'
        >
          <style>
            [data-composition-id="caption-camera-follow"] {
              --cf-accent: #ffd84d;
              --ink: #ffffff;
              position: absolute;
              inset: 0;
              overflow: hidden;
              background: transparent;
              pointer-events: none;
            }
            #cf-stage {
              position: absolute;
              inset: 0;
              overflow: hidden;
            }
            #cf-world {
              position: absolute;
              left: 0;
              top: 0;
              width: 0;
              height: 0;
              --amt: 0px;
            }
            .cf-word {
              position: absolute;
              white-space: nowrap;
              font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
              font-weight: 700;
              text-transform: uppercase;
              letter-spacing: 0.005em;
              line-height: 0.78;
              color: var(--ink);
              opacity: 0;
              --k: 0;
              filter: blur(calc(var(--k) * var(--amt)));
            }
            .cf-word.is-accent {
              color: var(--cf-accent);
            }
            #cf-vignette {
              position: absolute;
              inset: 0;
              background: radial-gradient(
                ellipse at 50% 50%,
                rgba(0, 0, 0, 0) 42%,
                rgba(0, 0, 0, 0.55) 100%
              );
            }
          </style>

          <div id="cf-stage">
            <div id="cf-world"></div>
          </div>
          <div id="cf-vignette"></div>

          <script src="https://cdn.jsdelivr.net/npm/gsap@3.14.2/dist/gsap.min.js"></script>
          <script>
            (function () {
              gsap.defaults({ immediateRender: false });

              /* Cubic bezier solver. Newton first, bisection as the fallback, so it is
                 exact and deterministic for every input. */
              function bezier(x1, y1, x2, y2) {
                function curve(t, a1, a2) {
                  var A = 1 - 3 * a2 + 3 * a1;
                  var B = 3 * a2 - 6 * a1;
                  var C = 3 * a1;
                  return ((A * t + B) * t + C) * t;
                }
                function slope(t, a1, a2) {
                  var A = 1 - 3 * a2 + 3 * a1;
                  var B = 3 * a2 - 6 * a1;
                  var C = 3 * a1;
                  return (3 * A * t + 2 * B) * t + C;
                }
                return function (p) {
                  if (p <= 0) return 0;
                  if (p >= 1) return 1;
                  var t = p;
                  for (var i = 0; i < 8; i++) {
                    var d = slope(t, x1, x2);
                    if (Math.abs(d) < 1e-6) break;
                    var e = curve(t, x1, x2) - p;
                    if (Math.abs(e) < 1e-7) return curve(t, y1, y2);
                    t -= e / d;
                  }
                  var lo = 0;
                  var hi = 1;
                  t = p;
                  for (var j = 0; j < 24; j++) {
                    var x = curve(t, x1, x2);
                    if (Math.abs(x - p) < 1e-7) break;
                    if (x > p) hi = t;
                    else lo = t;
                    t = (lo + hi) / 2;
                  }
                  return curve(t, y1, y2);
                };
              }

              /* Leaves the mark fast, spends most of its time arriving. */
              var EASE_STEP = bezier(0.31, 0, 0.11, 1);
              /* The closing pull back: slower to leave, glides a long way out. */
              var EASE_WIDE = bezier(0.42, 0, 0.14, 1);
              /* Word ink coming up. */
              var EASE_INK = bezier(0.2, 0.7, 0.3, 1);
              /* Blur rising into the move and wiped off out of it. */
              var EASE_BLUR_UP = bezier(0.2, 0.8, 0.4, 1);
              var EASE_BLUR_DOWN = bezier(0.5, 0, 0.2, 1);

              var vars =
                window.__hyperframes && window.__hyperframes.getVariables
                  ? window.__hyperframes.getVariables()
                  : {};

              /* Unrecognised overrides return to their declared defaults. */
              function pick(table, value, fallback) {
                return Object.prototype.hasOwnProperty.call(table, value) ? value : fallback;
              }

              var ACCENTS = {
                gold: "#ffd84d",
                green: "#34d399",
                blue: "#38bdf8",
                violet: "#a78bfa",
              };
              /* Framing scales the margin every camera pose is fitted with, so one
                 number moves the whole shot in or out without touching cadence. */
              var FRAMINGS = { tight: 0.82, standard: 1, wide: 1.25 };
              var SMEARS = { off: 0, subtle: 0.5, standard: 1, heavy: 1.9 };

              var ACCENT = ACCENTS[pick(ACCENTS, vars.accent, "gold")];
              var FRAMING = FRAMINGS[pick(FRAMINGS, vars.framing, "standard")];
              var SMEAR = SMEARS[pick(SMEARS, vars.smear, "standard")];

              var DUR = 9;
              var STEP = 0.52;
              var MOVE = 0.4;

              var WORDS = [
                { text: "write" },
                { text: "the" },
                { text: "html", accent: true },
                { text: "and" },
                { text: "the" },
                { text: "video", accent: true },
                { text: "renders" },
                { text: "itself" },
                { text: "no" },
                { text: "timeline" },
                { text: "no" },
                { text: "keyframes", accent: true },
                { text: "just" },
                { text: "code", accent: true },
              ];

              var world = document.getElementById("cf-world");
              var stage = document.getElementById("cf-stage");
              /* The runtime strips the root id on clone, so reach the root through a
                 descendant instead of getElementById. */
              var root = stage.parentElement;
              var FRAME_W = root.clientWidth || 1080;
              var FRAME_H = root.clientHeight || 1920;
              root.style.setProperty("--cf-accent", ACCENT);

              /* Base size is picked so the opening shot sits near 1:1. Everything after it
                 is a pull back, so the world is only ever scaled down and type stays crisp. */
              var BASE = Math.max(FRAME_W, FRAME_H) * 0.16;
              /* Each new word is this fraction of the current box height. */
              var RATIO = 0.72;
              var MARGIN = 1.36 * FRAMING;

              var ruler = document.createElement("div");
              ruler.style.cssText =
                "position:absolute;left:-99999px;top:0;white-space:nowrap;visibility:hidden;" +
                'font-family:"Helvetica Neue",Helvetica,Arial,sans-serif;font-weight:700;' +
                "text-transform:uppercase;letter-spacing:0.005em;line-height:0.78";
              world.appendChild(ruler);

              var box = null;
              WORDS.forEach(function (wd, i) {
                var fs = i === 0 ? BASE : (box.y1 - box.y0) * RATIO;
                ruler.style.fontSize = fs + "px";
                ruler.textContent = wd.text;
                var w = ruler.getBoundingClientRect().width;
                var h = fs * 0.78;
                var gap = fs * 0.07;

                var x, y;
                if (i === 0) {
                  x = 0;
                  y = 0;
                } else if ((box.x1 - box.x0) / (box.y1 - box.y0) < FRAME_W / FRAME_H) {
                  /* block is narrower than the frame, so grow sideways: to the right of
                     everything, sitting on the same baseline */
                  x = box.x1 + gap;
                  y = box.y1 - h;
                } else {
                  /* block is already wide enough, so grow downward: onto a new line under
                     everything, left edges aligned */
                  x = box.x0;
                  y = box.y1 + gap;
                }

                wd.fs = fs;
                wd.x = x;
                wd.y = y;

                box = box
                  ? {
                      x0: Math.min(box.x0, x),
                      y0: Math.min(box.y0, y),
                      x1: Math.max(box.x1, x + w),
                      y1: Math.max(box.y1, y + h),
                    }
                  : { x0: x, y0: y, x1: x + w, y1: y + h };
                wd.box = { x0: box.x0, y0: box.y0, x1: box.x1, y1: box.y1 };
              });
              world.removeChild(ruler);

              var FULL = box;

              function poseFor(b, margin) {
                var bw = (b.x1 - b.x0) * margin;
                var bh = (b.y1 - b.y0) * margin;
                var s = Math.min(FRAME_W / bw, FRAME_H / bh);
                return {
                  x: FRAME_W / 2 - (s * (b.x0 + b.x1)) / 2,
                  y: FRAME_H / 2 - (s * (b.y0 + b.y1)) / 2,
                  scale: s,
                };
              }

              var els = WORDS.map(function (wd) {
                var el = document.createElement("div");
                el.className = "cf-word" + (wd.accent ? " is-accent" : "");
                el.textContent = wd.text;
                el.style.left = wd.x + "px";
                el.style.top = wd.y + "px";
                el.style.fontSize = wd.fs + "px";
                world.appendChild(el);
                return el;
              });

              /* Re-derive every framing box from what the browser actually laid out, so
                 the camera is fitted to real ink and never to arithmetic that drifted. */
              var run = null;
              els.forEach(function (el, i) {
                var r = {
                  x0: el.offsetLeft,
                  y0: el.offsetTop,
                  x1: el.offsetLeft + el.offsetWidth,
                  y1: el.offsetTop + el.offsetHeight,
                };
                run = run
                  ? {
                      x0: Math.min(run.x0, r.x0),
                      y0: Math.min(run.y0, r.y0),
                      x1: Math.max(run.x1, r.x1),
                      y1: Math.max(run.y1, r.y1),
                    }
                  : r;
                WORDS[i].box = { x0: run.x0, y0: run.y0, x1: run.x1, y1: run.y1 };
              });
              FULL = run;

              /* Rest state is pinned outside the timeline. */
              var first = poseFor(WORDS[0].box, MARGIN);
              gsap.set(world, {
                transformOrigin: "0 0",
                x: first.x,
                y: first.y,
                scale: first.scale,
              });
              gsap.set(els, { opacity: 0, "--k": 0 });
              gsap.set(world, { "--amt": "0px" });
              /* The first word is already on the page when the shot opens, so frame zero
                 is never empty. */
              gsap.set(els[0], { opacity: 1 });

              var tl = gsap.timeline({ paused: true });
              /* Peak smear at the rim of the frame, in screen pixels. */
              var BLUR = FRAME_W * 0.026 * SMEAR;
              var HALF_DIAG = Math.sqrt(FRAME_W * FRAME_W + FRAME_H * FRAME_H) / 2;

              /* Radial blur, the way a real zoom smears: a point far from the centre of
                 the move sweeps across more of the frame than one sitting on it, so it
                 streaks more. Each word gets its own share, --k, of one shared amount,
                 --amt, which is the only thing that animates. The share is fixed for the
                 length of a move and set with the camera, so this stays one tween per
                 move rather than one per word per move. --amt is authored in world units,
                 because a filter on a scaled child is applied before the scale, so the
                 screen blur has to be divided back out by the camera scale. */
              function smear(centre, scale, count, at, up, down, peak) {
                for (var j = 0; j < count; j++) {
                  var el = els[j];
                  var cx = el.offsetLeft + el.offsetWidth / 2;
                  var cy = el.offsetTop + el.offsetHeight / 2;
                  var d =
                    (scale *
                      Math.sqrt(
                        (cx - centre.x) * (cx - centre.x) + (cy - centre.y) * (cy - centre.y),
                      )) /
                    HALF_DIAG;
                  tl.set(el, { "--k": (0.2 + 1.15 * Math.min(1, d)).toFixed(3) }, at);
                }
                var amt = peak / scale;
                tl.fromTo(
                  world,
                  { "--amt": "0px" },
                  { "--amt": amt + "px", duration: up, ease: EASE_BLUR_UP },
                  at,
                );
                tl.to(world, { "--amt": "0px", duration: down, ease: EASE_BLUR_DOWN }, at + up);
              }

              WORDS.forEach(function (wd, i) {
                var t = i * STEP;
                if (i === 0) return;

                tl.fromTo(els[i], { opacity: 0 }, { opacity: 1, duration: 0.16, ease: EASE_INK }, t);

                var p = poseFor(wd.box, MARGIN);
                tl.to(world, { x: p.x, y: p.y, scale: p.scale, duration: MOVE, ease: EASE_STEP }, t);

                smear(
                  { x: (wd.box.x0 + wd.box.x1) / 2, y: (wd.box.y0 + wd.box.y1) / 2 },
                  p.scale,
                  i + 1,
                  t,
                  MOVE * 0.24,
                  MOVE * 0.44,
                  BLUR,
                );
              });

              /* The resolve: the same pull back, carried all the way out. */
              var wide = poseFor(FULL, 1.2 * FRAMING);
              var wideAt = (WORDS.length - 1) * STEP + 0.62;
              tl.to(
                world,
                {
                  x: wide.x,
                  y: wide.y,
                  scale: wide.scale,
                  duration: 0.94,
                  ease: EASE_WIDE,
                },
                wideAt,
              );
              smear(
                { x: (FULL.x0 + FULL.x1) / 2, y: (FULL.y0 + FULL.y1) / 2 },
                wide.scale,
                els.length,
                wideAt,
                0.3,
                0.58,
                BLUR * 0.8,
              );

              tl.set({}, {}, DUR);
              tl.seek(0);

              window.__timelines = window.__timelines || {};
              window.__timelines["caption-camera-follow"] = tl;
            })();
          </script>
        </div>
      </template>
    </body>
  </html>
  ```
</Accordion>

Tagged `captions` `caption-style` `camera` `typography` `motion-primitive` `portrait`.

## Related topics

* [Browse the complete Catalog](/catalog)
* [Add assets and Catalog items in Studio](/studio/assets-and-blocks)
* [Build a richer composition](/go-further)