/* 3DStep viewer stylesheet.
 *
 * Inlined verbatim into every generated page and loaded with <link> by the
 * designer. Every color is a theme token (`--part-fill` and the rest, SPEC 10.1)
 * read through an internal `--tds-*` variable that carries the default palette,
 * so the viewer also renders without any theme CSS (the harness, a bare
 * designer preview). The layout numbers come from the behavior variables the
 * renderer emits (`--panel-max`, `--font-scale`, `--view-aspect`,
 * `--view-min-h`, `--view-max-h`), again with defaults.
 *
 * Layout (SPEC 9.2): .tds > .tds-main (.tds-view + .tds-panel) + .tds-bar. The
 * view and the panel sit side by side, the bar (hint and credit) under the view;
 * `.tds.is-stacked` (set by the viewer from the root's width and
 * `data-panel-stack-breakpoint`) puts the panel under the view and the bar under
 * the panel; `[data-placement="overlay"]` floats the text over the view; `.is-fs`
 * fills the screen. Class prefix: `tds-`. State classes: is-stacked, is-fs,
 * is-active, is-flying, is-ready, is-touch, is-played, is-playing-all.
 */

/* ── Tokens with their defaults (light), then dark ─────────────────── */

.tds {
  --tds-bg: var(--bg, #ffffff);
  --tds-text: var(--text, #1a1a1a);
  --tds-tip-bg: var(--tip-bg, #ffffff);
  --tds-tip-border: var(--tip-border, #d0d0d0);
  --tds-tip-shadow: var(--tip-shadow, rgba(0, 0, 0, .12));
  --tds-divider: var(--divider, #e5e5e5);
  --tds-desc: var(--desc-color, #555);
  --tds-scroll-thumb: var(--scroll-thumb, rgba(0, 0, 0, .22));
  --tds-scroll-track: var(--scroll-track, transparent);
  --tds-accent: var(--accent, #2563eb);
  --tds-view-bg: var(--view-bg, #ffffff);
  --tds-part-fill: var(--part-fill, #ffffff);
  --tds-part-edge: var(--part-edge, #3a3a3a);
  --tds-highlight-fill: var(--highlight-fill, #b8cff5);
  --tds-highlight-edge: var(--highlight-edge, #2f5fb3);
  --tds-arrow: var(--arrow, #2563eb);
  --tds-arrow-edge: var(--arrow-edge, #1e3a8a);
  --tds-label-bg: var(--label-bg, rgba(255, 255, 255, .92));
  --tds-label-text: var(--label-text, #1a1a1a);
  --tds-label-line: var(--label-line, #3a3a3a);
  --tds-ghost-opacity: var(--ghost-opacity, 0.25);
  --tds-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .tds {
    --tds-bg: var(--bg, #131313);
    --tds-text: var(--text, #e0e0e0);
    --tds-tip-bg: var(--tip-bg, #1e1e1e);
    --tds-tip-border: var(--tip-border, #3a3a3a);
    --tds-tip-shadow: var(--tip-shadow, rgba(0, 0, 0, .4));
    --tds-divider: var(--divider, #333);
    --tds-desc: var(--desc-color, #aaa);
    --tds-scroll-thumb: var(--scroll-thumb, rgba(255, 255, 255, .20));
    --tds-accent: var(--accent, #60a5fa);
    --tds-view-bg: var(--view-bg, #1a1a1a);
    --tds-part-fill: var(--part-fill, #2a2a2a);
    --tds-part-edge: var(--part-edge, #d0d0d0);
    --tds-highlight-fill: var(--highlight-fill, #2f4f8f);
    --tds-highlight-edge: var(--highlight-edge, #9cc0ff);
    --tds-arrow: var(--arrow, #60a5fa);
    --tds-arrow-edge: var(--arrow-edge, #cfe2ff);
    --tds-label-bg: var(--label-bg, rgba(30, 30, 30, .92));
    --tds-label-text: var(--label-text, #e0e0e0);
    --tds-label-line: var(--label-line, #bbbbbb);
    --tds-ghost-opacity: var(--ghost-opacity, 0.3);
    --tds-scheme: dark;
  }
}

:root[data-theme="dark"] .tds {
  --tds-bg: var(--bg, #131313);
  --tds-text: var(--text, #e0e0e0);
  --tds-tip-bg: var(--tip-bg, #1e1e1e);
  --tds-tip-border: var(--tip-border, #3a3a3a);
  --tds-tip-shadow: var(--tip-shadow, rgba(0, 0, 0, .4));
  --tds-divider: var(--divider, #333);
  --tds-desc: var(--desc-color, #aaa);
  --tds-scroll-thumb: var(--scroll-thumb, rgba(255, 255, 255, .20));
  --tds-accent: var(--accent, #60a5fa);
  --tds-view-bg: var(--view-bg, #1a1a1a);
  --tds-part-fill: var(--part-fill, #2a2a2a);
  --tds-part-edge: var(--part-edge, #d0d0d0);
  --tds-highlight-fill: var(--highlight-fill, #2f4f8f);
  --tds-highlight-edge: var(--highlight-edge, #9cc0ff);
  --tds-arrow: var(--arrow, #60a5fa);
  --tds-arrow-edge: var(--arrow-edge, #cfe2ff);
  --tds-label-bg: var(--label-bg, rgba(30, 30, 30, .92));
  --tds-label-text: var(--label-text, #e0e0e0);
  --tds-label-line: var(--label-line, #bbbbbb);
  --tds-ghost-opacity: var(--ghost-opacity, 0.3);
  --tds-scheme: dark;
}

/* ── The standalone page (boot() adds `tds-page` to <html>) ───────── */

html.tds-page, html.tds-page body { margin: 0; padding: 0; }
html.tds-page body {
  background: var(--bg, #ffffff);
  color: var(--text, #1a1a1a);
  font-family: var(--ui-font, Roboto, system-ui, sans-serif);
}
@media (prefers-color-scheme: dark) {
  html.tds-page:not([data-theme="light"]) body { background: var(--bg, #131313); color: var(--text, #e0e0e0); }
}
html.tds-page[data-theme="dark"] body { background: var(--bg, #131313); color: var(--text, #e0e0e0); }

/* ── Root ─────────────────────────────────────────────────────────── */

.tds {
  position: relative;
  display: block;
  box-sizing: border-box;
  width: 100%;
  margin: 0;
  padding: 0;
  font-family: var(--ui-font, Roboto, system-ui, sans-serif);
  font-size: calc(15px * var(--font-scale, 1));
  line-height: 1.45;
  color: var(--tds-text);
  -webkit-text-size-adjust: 100%;
  outline: none;
}
.tds *, .tds *::before, .tds *::after { box-sizing: border-box; }
.tds:focus-visible { outline: 2px solid var(--tds-accent); outline-offset: 2px; }
.tds button {
  font: inherit;
  color: inherit;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}
.tds button:focus-visible { outline: 2px solid var(--tds-accent); outline-offset: 2px; }
.tds a { color: var(--tds-accent); }
.tds code {
  font-family: var(--label-font, ui-monospace, "Roboto Mono", Menlo, monospace);
  font-size: .92em;
  padding: .05em .3em;
  border-radius: 4px;
  background: color-mix(in srgb, var(--tds-text) 10%, transparent);
}

/* ── Main layout: view beside the panel ───────────────────────────── */

.tds-main {
  position: relative;
  display: flex;
  flex-direction: row;
  align-items: stretch;
  width: 100%;
}
.tds-view {
  position: relative;
  flex: 1 1 auto;
  min-width: 0;
  width: 100%;
  aspect-ratio: var(--view-aspect, 1.6);
  min-height: var(--view-min-h, 320px);
  max-height: var(--view-max-h, 720px);
  background: var(--tds-view-bg);
  overflow: hidden;
  touch-action: pan-y;
  user-select: none;
  -webkit-user-select: none;
}
.tds-canvas {
  display: block;
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  outline: none;
  touch-action: pan-y;
}
.tds.is-active .tds-canvas { touch-action: none; }
.tds.is-active .tds-view { touch-action: none; }
.tds.is-active .tds-view::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  box-shadow: inset 0 0 0 2px var(--tds-accent);
  z-index: 3;
}

/* The panel: absolutely positioned beside the view and the bar under it (the
   root is its containing block), so its height is theirs and it scrolls inside;
   the row and the bar make room for it. Stacked, it goes back in flow. The
   wheel scrolls the panel, then the page at its ends: on a docs page the
   page must scroll wherever the wheel lands (SPEC 9.9), and a panel with
   nothing to scroll passes the wheel straight on. */
.tds-panel {
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  width: var(--panel-max, min(360px, 40vw));
  max-width: 40vw;
  overflow: auto;
  background: var(--tds-tip-bg);
  border-left: 1px solid var(--tds-divider);
  scrollbar-width: thin;
  scrollbar-color: var(--tds-scroll-thumb) var(--tds-scroll-track);
}
.tds[data-placement="right"][data-controls="full"]:not(.is-stacked):not(.is-fs):not(.is-editor) .tds-main { position: static; padding-right: min(var(--panel-max, min(360px, 40vw)), 40vw); }
.tds[data-placement="right"][data-controls="full"]:not(.is-stacked):not(.is-fs):not(.is-editor) .tds-bar { margin-right: min(var(--panel-max, min(360px, 40vw)), 40vw); }
.tds-panel::-webkit-scrollbar { width: 8px; }
.tds-panel::-webkit-scrollbar-thumb { background: var(--tds-scroll-thumb); border-radius: 4px; }
.tds-panel::-webkit-scrollbar-track { background: var(--tds-scroll-track); }
/* A column at least as tall as the panel: the text takes the slack, so
   Previous and Next sit at the bottom however long the step's text is. */
.tds-panel-in { display: flex; flex-direction: column; min-height: 100%; padding: 14px 16px 0; }
.tds-panel-in > * { flex: none; }
.tds-panel-in > .tds-text { flex: 1 0 auto; }

/* Stacked (narrow, or panel_placement = below): panel under the view. */
.tds.is-stacked .tds-main, .tds[data-placement="below"] .tds-main { flex-direction: column; padding-right: 0; }
.tds.is-stacked .tds-panel, .tds[data-placement="below"] .tds-panel {
  position: static;
  width: auto;
  max-width: none;
  height: auto;
  overflow: hidden;
  border-left: 0;
  border-top: 1px solid var(--tds-divider);
}

/* Overlay: text and nav float over the bottom of the view, no step list. */
.tds[data-placement="overlay"] .tds-main { padding-right: 0; }
.tds[data-placement="overlay"] .tds-panel {
  position: absolute;
  left: 0;
  right: 0;
  top: auto;
  bottom: 0;
  width: auto;
  max-width: none;
  max-height: 55%;
  border: 0;
  border-top: 1px solid var(--tds-divider);
  background: color-mix(in srgb, var(--tds-tip-bg) 88%, transparent);
  -webkit-backdrop-filter: blur(6px);
  backdrop-filter: blur(6px);
  z-index: 4;
}
.tds[data-placement="overlay"] .tds-panel-head,
.tds[data-placement="overlay"] .tds-steps { display: none; }
.tds[data-placement="overlay"] .tds-panel-in { padding: 10px 14px 0; }

/* ── Fullscreen ───────────────────────────────────────────────────── */

.tds.is-fs, .tds:fullscreen {
  position: fixed;
  inset: 0;
  display: flex;
  flex-direction: column;
  width: 100%;
  height: 100%;
  z-index: 2147483000;
  background: var(--tds-view-bg);
}
.tds.is-fs .tds-main, .tds:fullscreen .tds-main { flex: 1 1 0; min-height: 0; padding-right: 0; flex-direction: row; }
.tds.is-fs .tds-view, .tds:fullscreen .tds-view { aspect-ratio: auto; height: 100%; max-height: none; min-height: 0; }
/* The page hidden behind a fullscreen viewer must not move when its panel
   reaches an end. */
.tds.is-fs .tds-panel, .tds:fullscreen .tds-panel {
  position: absolute;
  left: 0;
  right: 0;
  top: auto;
  bottom: 0;
  width: auto;
  max-width: none;
  max-height: 45%;
  overflow: auto;
  overscroll-behavior: contain;
  border: 0;
  border-top: 1px solid var(--tds-divider);
  background: color-mix(in srgb, var(--tds-tip-bg) 88%, transparent);
  -webkit-backdrop-filter: blur(6px);
  backdrop-filter: blur(6px);
  z-index: 4;
}
.tds.is-fs .tds-panel-head, .tds:fullscreen .tds-panel-head,
.tds.is-fs .tds-steps, .tds:fullscreen .tds-steps { display: none; }

/* ── Controls modes ───────────────────────────────────────────────── */

.tds[data-controls="minimal"] .tds-panel,
.tds[data-controls="none"] .tds-panel { display: none; }
.tds[data-controls="minimal"] .tds-main,
.tds[data-controls="none"] .tds-main { padding-right: 0; flex-direction: column; }
.tds[data-controls="none"] .tds-hud,
.tds[data-controls="none"] .tds-bar,
.tds[data-controls="none"] .tds-caption { display: none; }
.tds[data-controls="full"] .tds-hud-nav { display: none; }
.tds-caption {
  display: none;
  flex: none;
  width: 100%;
  padding: 6px 12px;
  font-size: .95em;
  color: var(--tds-text);
  background: var(--tds-tip-bg);
  border-top: 1px solid var(--tds-divider);
}
.tds[data-controls="minimal"] .tds-caption { display: block; }
.tds[data-controls="minimal"] .tds-caption:empty { display: none; }

/* ── Overlay: labels and leader lines ─────────────────────────────── */

.tds-overlay {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  overflow: visible;
  z-index: 2;
}
.tds-overlay line { stroke: var(--tds-label-line); stroke-width: 1.5; }
.tds-overlay circle { fill: var(--tds-label-line); }
.tds-labels { position: absolute; inset: 0; pointer-events: none; z-index: 2; overflow: hidden; }
.tds-label {
  position: absolute;
  left: 0;
  top: 0;
  max-width: 220px;
  padding: 3px 8px;
  border: 1px solid var(--tds-label-line);
  border-radius: 6px;
  background: var(--tds-label-bg);
  color: var(--tds-label-text);
  font-family: var(--label-font, var(--ui-font, Roboto, system-ui, sans-serif));
  font-size: calc(13px * var(--font-scale, 1));
  line-height: 1.3;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  box-shadow: 0 1px 4px var(--tds-tip-shadow);
  transition: opacity .25s ease;
  will-change: transform;
}
.tds.is-flying .tds-label, .tds.is-flying .tds-overlay { opacity: 0; }
.tds-overlay { transition: opacity .25s ease; }
.tds-label.is-off, .tds-overlay .is-off { display: none; }

/* ── HUD ──────────────────────────────────────────────────────────── */

.tds-hud {
  position: absolute;
  top: 8px;
  left: 8px;
  right: 8px;
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 8px;
  pointer-events: none;
  z-index: 5;
  font-size: calc(13px * var(--font-scale, 1));
}
.tds-hud > * { pointer-events: auto; }
.tds-hud-left, .tds-hud-right { display: flex; align-items: center; gap: 6px; }
.tds-counter {
  display: inline-block;
  padding: 4px 10px;
  border: 1px solid var(--tds-tip-border);
  border-radius: 999px;
  background: var(--tds-tip-bg);
  color: var(--tds-desc);
  font-family: var(--label-font, var(--ui-font, Roboto, system-ui, sans-serif));
  font-variant-numeric: tabular-nums;
  box-shadow: 0 1px 4px var(--tds-tip-shadow);
}
.tds-hud button, .tds-nav button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  min-width: 32px;
  height: 32px;
  padding: 0 8px;
  border: 1px solid var(--tds-tip-border);
  border-radius: 8px;
  background: var(--tds-tip-bg);
  color: var(--tds-text);
  box-shadow: 0 1px 4px var(--tds-tip-shadow);
  line-height: 1;
}
.tds-hud button:hover, .tds-nav button:hover:not(:disabled) { border-color: var(--tds-accent); color: var(--tds-accent); }
.tds-hud button:disabled, .tds-nav button:disabled { opacity: .45; cursor: default; }
.tds-hud button svg { width: 18px; height: 18px; display: block; }
.tds-hud button.is-on { color: var(--tds-accent); border-color: var(--tds-accent); }
.tds-hud button[hidden] { display: none; }
.tds-hud .tds-glyph { font-size: 17px; font-weight: 600; }
.tds-btn-fs .i-min, .tds.is-fs .tds-btn-fs .i-max, .tds:fullscreen .tds-btn-fs .i-max { display: none; }
.tds.is-fs .tds-btn-fs .i-min, .tds:fullscreen .tds-btn-fs .i-min { display: block; }
.tds-btn-play .i-reset, .tds.is-played .tds-btn-play .i-play { display: none; }
.tds.is-played .tds-btn-play .i-reset { display: block; }
.tds-btn-playall .i-pause, .tds.is-playing-all .tds-btn-playall .i-play { display: none; }
.tds.is-playing-all .tds-btn-playall .i-pause { display: block; }
.tds.is-playing-all .tds-btn-playall { color: var(--tds-accent); border-color: var(--tds-accent); }

/* ── Bar: the hint and the credit ─────────────────────────────────── */

.tds-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 2px 16px;
  padding: 5px 12px;
  font-size: calc(12px * var(--font-scale, 1));
  line-height: 1.4;
  color: var(--tds-desc);
  background: var(--tds-tip-bg);
  border-top: 1px solid var(--tds-divider);
}
.tds-hint { flex: 1 1 auto; min-width: 0; }
.tds-credit { margin-left: auto; white-space: nowrap; }
.tds-credit a { color: inherit; font-weight: 600; text-decoration: none; }
.tds-credit a:hover { color: var(--tds-accent); text-decoration: underline; }

/* ── Fallback box (no WebGL, load errors, still loading) ──────────── */

.tds-fallback {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 16px;
  text-align: center;
  color: var(--tds-text);
  background: var(--tds-view-bg);
  z-index: 6;
}
.tds-fallback[hidden] { display: none; }
.tds-fallback p { margin: 0; max-width: 36em; }
.tds-fallback .tds-fallback-detail { font-size: .9em; color: var(--tds-desc); }
.tds-fallback a { color: var(--tds-accent); }
.tds-spinner {
  width: 28px;
  height: 28px;
  border: 3px solid var(--tds-divider);
  border-top-color: var(--tds-accent);
  border-radius: 50%;
  animation: tds-spin .9s linear infinite;
}
@keyframes tds-spin { to { transform: rotate(360deg); } }

/* ── Panel content ────────────────────────────────────────────────── */

.tds-panel-head { padding-bottom: 10px; margin-bottom: 10px; border-bottom: 1px solid var(--tds-divider); }
.tds-title { font-size: 1.1em; font-weight: 600; line-height: 1.3; }
.tds-desc { margin-top: 4px; font-size: .92em; color: var(--tds-desc); }
.tds-desc:empty, .tds-panel-head[hidden] { display: none; }

.tds-steps {
  list-style: none;
  margin: 0 0 10px;
  padding: 0 0 10px;
  border-bottom: 1px solid var(--tds-divider);
  font-size: .92em;
}
.tds-steps[hidden] { display: none; }
.tds-steps li { margin: 0; padding: 0; }
.tds-steps button {
  display: flex;
  align-items: baseline;
  gap: 8px;
  width: 100%;
  padding: 4px 6px;
  border: 0;
  border-radius: 6px;
  background: none;
  text-align: left;
  color: var(--tds-desc);
}
.tds-steps button:hover { background: color-mix(in srgb, var(--tds-accent) 10%, transparent); color: var(--tds-text); }
.tds-steps .tds-step-n {
  flex: none;
  min-width: 1.6em;
  font-family: var(--label-font, var(--ui-font, Roboto, system-ui, sans-serif));
  font-variant-numeric: tabular-nums;
  color: var(--tds-desc);
}
.tds-steps li.is-current button { color: var(--tds-text); font-weight: 600; background: color-mix(in srgb, var(--tds-accent) 14%, transparent); }
.tds-steps li.is-current .tds-step-n { color: var(--tds-accent); }
.tds-steps li.is-done .tds-step-n { color: var(--tds-accent); opacity: .7; }

.tds-text { min-height: 2em; }
.tds-step-title { margin: 0 0 6px; font-size: 1.05em; font-weight: 600; line-height: 1.3; }
.tds-step-kicker {
  font-family: var(--label-font, var(--ui-font, Roboto, system-ui, sans-serif));
  font-size: .78em;
  color: var(--tds-accent);
  letter-spacing: .04em;
  text-transform: uppercase;
}
.tds-parts { margin: 0 0 8px; font-size: .9em; color: var(--tds-desc); }
.tds-parts:empty { display: none; }
.tds-parts span { color: var(--tds-text); }
.tds-body p { margin: 0 0 .7em; }
.tds-body p:last-child { margin-bottom: 0; }
.tds-note {
  display: flex;
  gap: 8px;
  margin-top: 10px;
  padding: 8px 10px;
  border: 1px solid var(--tds-tip-border);
  border-left: 3px solid var(--tds-accent);
  border-radius: 6px;
  font-size: .92em;
  background: color-mix(in srgb, var(--tds-accent) 7%, transparent);
}
.tds-note:empty { display: none; }
.tds-note svg { flex: none; width: 16px; height: 16px; margin-top: 2px; color: var(--tds-accent); }

/* Sticky, so Previous and Next stay in reach while a long step scrolls the
   panel beside the view; it carries the panel's bottom padding. */
.tds-nav {
  position: sticky;
  bottom: 0;
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 14px;
  padding: 10px 0 12px;
  border-top: 1px solid var(--tds-divider);
  background: var(--tds-tip-bg);
}
.tds[data-placement="overlay"] .tds-nav, .tds.is-fs .tds-nav, .tds:fullscreen .tds-nav { padding-bottom: 10px; background: none; }
.tds-nav button { flex: none; height: 34px; padding: 0 12px; }
.tds-nav button svg { width: 16px; height: 16px; }
.tds-nav .tds-btn-playall { width: 34px; padding: 0; }
.tds-progress { flex: 1 1 auto; height: 4px; border-radius: 2px; background: var(--tds-divider); overflow: hidden; }
.tds-progress-bar { height: 100%; width: 0; background: var(--tds-accent); transition: width .3s ease; }

/* ── Narrow screens ───────────────────────────────────────────────── */

@media (max-width: 480px) {
  .tds { font-size: calc(14px * var(--font-scale, 1)); }
  .tds-panel-in { padding: 12px 12px 0; }
  .tds-nav { padding-bottom: 10px; }
  .tds-hud { top: 6px; left: 6px; right: 6px; }
  .tds-hud button, .tds-nav button { min-width: 36px; height: 36px; }
  .tds-nav button { flex: 1 1 auto; }
  .tds-nav .tds-btn-playall { flex: none; width: 48px; }
  .tds-nav .tds-progress { order: -1; flex: 1 0 100%; margin-bottom: 8px; }
  .tds-nav { flex-wrap: wrap; }
  .tds-label { max-width: 160px; }
}

/* ── Editor mode ──────────────────────────────────────────────────── */

.tds.is-editor .tds-bar, .tds.is-editor .tds-panel, .tds.is-editor .tds-caption { display: none; }
.tds.is-editor .tds-main { padding-right: 0; }
.tds.is-editor .tds-view { aspect-ratio: auto; height: 100%; min-height: 0; max-height: none; }
.tds.is-editor, .tds.is-editor .tds-main { height: 100%; }

/* ── Reduced motion ───────────────────────────────────────────────── */

@media (prefers-reduced-motion: reduce) {
  .tds *, .tds *::before, .tds *::after { transition: none !important; animation-duration: .01s !important; }
}