/* Editorial palette + scene-engine shell. Tokens consistent with the
   sibling gradient-descent-viz so the lecture's visual identity carries. */

:root,
:root[data-theme="light"] {
  --bg: #f9f7f1;
  --ink: #1a1a1a;
  --ink-secondary: #6b6b6b;
  --rule: #d8d4ca;
  --card-bg: #ffffff;

  /* CNN-specific tokens */
  --cnn-pos: #2f6cb1;          /* blue: positive weight, fires, match */
  --cnn-neg: #b8323a;          /* red: negative weight */
  --cnn-neutral: #f0ece2;      /* heatmap mid-point */
  --cnn-accent: #c08a3e;       /* amber: highlight */
  --cnn-purple: #7a5c8c;       /* purple: tertiary, used sparingly */
  --cnn-green: #4a8b6b;        /* green: tertiary, used sparingly */

  /* Categorical classes (segmentation) */
  --class-sky: #6ea3dc;
  --class-grass: #4a8b6b;
  --class-sun: #c08a3e;
  --class-tree: #7a5c8c;
  --class-person: #b8323a;
}

:root[data-theme="dark"] {
  --bg: #181612;
  --ink: #ece7d9;
  --ink-secondary: #8a8579;
  --rule: #383530;
  --card-bg: #211e19;

  --cnn-pos: #6ea3dc;
  --cnn-neg: #d77078;
  --cnn-neutral: #2a2722;
  --cnn-accent: #d6a766;
  --cnn-purple: #b394cb;
  --cnn-green: #6fae8a;

  --class-sky: #6ea3dc;
  --class-grass: #6fae8a;
  --class-sun: #d6a766;
  --class-tree: #b394cb;
  --class-person: #d77078;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Inter", "Segoe UI", Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.5;
}

/* ---------------------------------------------------------------------------
   Topbar
   --------------------------------------------------------------------------- */

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 24px;
  border-bottom: 1px solid var(--rule);
  font-size: 12px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--ink-secondary);
}

.topbar .brand { font-weight: 600; }
.topbar .scene-title {
  font-family: "Iowan Old Style", Palatino, Georgia, serif;
  font-style: italic;
  font-size: 14px;
  letter-spacing: 0;
  text-transform: none;
  color: var(--ink-secondary);
  flex: 1 1 auto;
  text-align: center;
  padding: 0 24px;
}

.topbar .right-cluster { display: flex; gap: 8px; align-items: center; }

.theme-toggle, .pager-btn {
  background: transparent;
  color: var(--ink-secondary);
  border: 1px solid var(--rule);
  border-radius: 4px;
  padding: 4px 10px;
  font: inherit;
  font-size: 11px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  cursor: pointer;
}
.theme-toggle:hover, .pager-btn:hover {
  color: var(--ink);
  border-color: var(--ink-secondary);
}
.pager-btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

/* ---------------------------------------------------------------------------
   Stage / scene engine
   --------------------------------------------------------------------------- */

.stage {
  position: relative;
  max-width: 1200px;
  margin: 16px auto 32px;
  padding: 0 24px;
  min-height: calc(100vh - 130px);
}

.scene {
  opacity: 0;
  pointer-events: none;
  position: absolute;
  top: 0;
  left: 24px;
  right: 24px;
  transition: opacity 180ms ease-out;
}
.scene.active {
  opacity: 1;
  pointer-events: auto;
  position: relative;
  left: 0;
  right: 0;
}

/* Dot pager in the topbar */
.dot-pager {
  display: flex;
  gap: 6px;
  align-items: center;
}
.dot-pager .dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--rule);
  border: none;
  padding: 0;
  cursor: pointer;
}
.dot-pager .dot.active { background: var(--ink); }
.dot-pager .dot:hover { background: var(--ink-secondary); }

/* ---------------------------------------------------------------------------
   Hero block
   --------------------------------------------------------------------------- */

.hero h1 {
  font-family: "Iowan Old Style", Palatino, Georgia, serif;
  font-weight: 500;
  font-size: 28px;
  margin: 0 0 6px;
  letter-spacing: -0.005em;
}

.hero .subtitle {
  font-family: "Iowan Old Style", Palatino, Georgia, serif;
  font-style: italic;
  font-size: 16px;
  color: var(--ink-secondary);
  margin: 0 0 18px;
}

.hero .lede {
  font-family: "Iowan Old Style", Palatino, Georgia, serif;
  font-size: 16.5px;
  line-height: 1.55;
  margin: 0 0 14px;
  max-width: 60ch;
}

/* ---------------------------------------------------------------------------
   Cards
   --------------------------------------------------------------------------- */

.card {
  background: var(--card-bg);
  border: 1px solid var(--rule);
  border-radius: 4px;
  padding: 10px 14px;
}

/* ---------------------------------------------------------------------------
   Controls
   --------------------------------------------------------------------------- */

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  align-items: center;
  padding: 8px 4px;
  border-top: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
  margin-top: 10px;
}

.control-group {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 12px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--ink-secondary);
}

.control-group label { white-space: nowrap; }

.control-group input[type="range"] {
  accent-color: var(--cnn-pos);
  height: 4px;
  width: 130px;
}

.control-group output, .control-group .control-value {
  font-family: "SF Mono", Menlo, monospace;
  font-size: 12px;
  font-variant-numeric: tabular-nums;
  color: var(--ink);
  min-width: 36px;
  text-align: right;
  text-transform: none;
  letter-spacing: 0;
}

.control-group select, .control-group button {
  background: var(--card-bg);
  color: var(--ink);
  border: 1px solid var(--rule);
  border-radius: 3px;
  padding: 3px 8px;
  font: inherit;
  font-size: 12px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  cursor: pointer;
}
.control-group button:hover, .control-group select:hover {
  border-color: var(--ink-secondary);
}
.control-group button.primary {
  background: var(--cnn-pos);
  color: white;
  border-color: var(--cnn-pos);
}
.control-group button.primary:hover { filter: brightness(1.06); }
.control-group button:disabled { opacity: 0.4; cursor: not-allowed; }

/* ---------------------------------------------------------------------------
   Captions / footnotes / formula blocks
   --------------------------------------------------------------------------- */

.caption {
  font-family: "Iowan Old Style", Palatino, Georgia, serif;
  font-style: italic;
  font-size: 14px;
  color: var(--ink-secondary);
  margin: 8px 4px 0;
  min-height: 1.55em;
}

.footnote {
  font-size: 11px;
  color: var(--ink-secondary);
  border-top: 1px solid var(--rule);
  padding-top: 8px;
  margin-top: 14px;
  text-align: right;
  font-style: italic;
}
.footnote kbd {
  font-family: "SF Mono", Menlo, monospace;
  font-size: 10px;
  border: 1px solid var(--rule);
  border-radius: 3px;
  padding: 0 4px;
  background: var(--card-bg);
  color: var(--ink);
  font-style: normal;
}

.formula-block {
  margin: 10px 0;
  text-align: center;
}
.formula-block .katex { color: var(--ink); }

/* ---------------------------------------------------------------------------
   Cluster classes (segmentation overlay)
   --------------------------------------------------------------------------- */

.class-sky    { fill: var(--class-sky);    stroke: var(--class-sky); color: var(--class-sky); }
.class-grass  { fill: var(--class-grass);  stroke: var(--class-grass); color: var(--class-grass); }
.class-sun    { fill: var(--class-sun);    stroke: var(--class-sun); color: var(--class-sun); }
.class-tree   { fill: var(--class-tree);   stroke: var(--class-tree); color: var(--class-tree); }
.class-person { fill: var(--class-person); stroke: var(--class-person); color: var(--class-person); }

/* ---------------------------------------------------------------------------
   Generic two-column scene layout (input | output)
   --------------------------------------------------------------------------- */

.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  align-items: start;
  margin-top: 14px;
}

.three-col {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 18px;
  align-items: start;
  margin-top: 14px;
}

.col-stack {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.col-label {
  font-family: "Iowan Old Style", Palatino, Georgia, serif;
  font-style: italic;
  font-size: 13px;
  color: var(--ink-secondary);
  text-align: center;
}

/* Canvas container — locks dimensions to prevent flex/grid auto-stretch
   silently squashing canvases under headless rendering. */
.canvas-host {
  display: flex;
  align-items: center;
  justify-content: center;
  flex: 0 0 auto;
}
.canvas-host canvas { display: block; flex: 0 0 auto; }

/* ----------------------------------------------------------------------
   U-Net mini-map. A reusable "you are here" diagram of the full U-Net,
   used as a sidebar in scenes that focus on one specific component.
   See window.UNET.mountUNetMiniMap.
   ---------------------------------------------------------------------- */
.unet-mini {
  display: flex;
  flex-direction: column;
  gap: 4px;
  align-items: center;
  padding: 12px 14px;
  background: var(--card-bg);
  border: 1px solid var(--rule);
  border-radius: 4px;
}
.unet-mini-title {
  font-size: 10px;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--ink-secondary);
  font-family: "SF Mono", Menlo, monospace;
  align-self: stretch;
  text-align: left;
}
.unet-mini-svg {
  display: block;
}
.unet-mini-label {
  font-size: 11px;
  font-style: italic;
  color: var(--ink-secondary);
  text-align: center;
  max-width: 220px;
  line-height: 1.35;
}

/* Tensor bars (rest). */
.unet-mini-bar {
  stroke-width: 0.5;
}
.unet-mini-bar-tensor {
  fill: #7aa6c7;            /* same blue as scene 0 tensor bars */
  stroke: #7aa6c7;
}
:root[data-theme="dark"] .unet-mini-bar-tensor {
  fill: #5b8db3;
  stroke: #5b8db3;
}
.unet-mini-bar-skip-half {
  fill: #d2a05a;            /* amber for the skip half of concat tensors */
}
:root[data-theme="dark"] .unet-mini-bar-skip-half {
  fill: #b08550;
}
.unet-mini-bar-out {
  fill: #b07eb0;            /* purple for the 1×1 head */
}
:root[data-theme="dark"] .unet-mini-bar-out {
  fill: #9a6b9a;
}
.unet-mini-bar-argmax {
  fill: var(--ink-secondary);
}

/* Operation arrows (rest). */
.unet-mini-arrow {
  fill: none;
}
.unet-mini-arrow-conv     { stroke: #5aa64a; stroke-width: 1.2; }
.unet-mini-arrow-pool     { stroke: #c95a5a; stroke-width: 1.4; }
.unet-mini-arrow-upconv   { stroke: #9067c2; stroke-width: 1.4; }
.unet-mini-arrow-onexone  { stroke: #3a8fb7; stroke-width: 1.2; }
.unet-mini-arrow-argmax   { stroke: var(--ink-secondary); stroke-width: 0.8; stroke-dasharray: 2 2; }
.unet-mini-arrow-concat   { stroke: var(--ink-secondary); stroke-width: 1; opacity: 0.85; }
.unet-mini-skip {
  stroke: var(--ink-secondary);
  stroke-width: 1;
  stroke-dasharray: 3 2;
  opacity: 0.7;
}

/* Highlight states. */
.unet-mini-bar-glow {
  fill: var(--accent, #d97a1f);
  opacity: 0.18;
  pointer-events: none;
}
.unet-mini-bar-ring {
  fill: none;
  stroke: var(--accent, #d97a1f);
  stroke-width: 2;
  pointer-events: none;
}
.unet-mini-arrow.unet-mini-lit {
  stroke: var(--accent, #d97a1f);
  stroke-width: 2.2;
  opacity: 1;
  stroke-dasharray: none;
}
.unet-mini-skip.unet-mini-lit {
  stroke: var(--accent, #d97a1f);
  stroke-width: 2;
  opacity: 1;
  stroke-dasharray: none;
}
.unet-mini-bar.unet-mini-dim,
.unet-mini-arrow.unet-mini-dim,
.unet-mini-skip.unet-mini-dim,
[data-tensor-id].unet-mini-dim { opacity: 0.3; }

/* Landmark labels above the bars. */
.unet-mini-label-text {
  font-family: "SF Mono", Menlo, monospace;
  font-size: 8px;
  fill: var(--ink-secondary);
  pointer-events: none;
}