:root {
  --bg: #0f1419; --bg2: #161b22; --panel: #1a1f2e; --panel-2: #202940;
  --zinc-700: #3f3f46; --zinc-600: #52525b; --zinc-500: #71717a;
  --zinc-400: #a1a1aa; --zinc-300: #d4d4d8; --zinc-200: #e4e4e7;
  --zinc-100: #f4f4f5; --zinc-50:  #fafafa;
  --syntax-keyword: #82AAFF; --syntax-string:  #C3E88D;
  --syntax-fn: #FFCB6B; --syntax-const: #F78C6C;
  --syntax-comment: #546E7A; --syntax-text: #A6ACCD;
  --red: #f87171; --green: #4ade80; --amber: #fbbf24;
  --font-sans: -apple-system, BlinkMacSystemFont, "Inter", "Segoe UI", Roboto, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: var(--font-sans);
  color: var(--zinc-200);
  min-height: 100vh;
  line-height: 1.55;
  background: var(--bg);
  isolation: isolate;
}

.bg-layer {
  position: fixed; inset: 0; z-index: 0;
  background-image: url("/classroom.jpg");
  background-size: cover; background-position: center;
  filter: blur(6px) saturate(1.15);
  transform: scale(1.15);
  pointer-events: none;
}
.bg-tint { position: fixed; inset: 0; background: rgba(15,20,25,0.6); z-index: 1; pointer-events: none; }

.chrome {
  position: relative; z-index: 10;
  display: flex; align-items: center; gap: 12px;
  padding: 12px 20px;
  background: rgba(0,0,0,0.85);
  backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--zinc-700);
}
.chrome .dots { display: flex; gap: 6px; }
.chrome .dots span { width: 14px; height: 14px; border-radius: 50%; }
.chrome .dots .r { background: #ff5f57; }
.chrome .dots .y { background: #febc2e; }
.chrome .dots .g { background: #28c840; }
.chrome .file {
  font-family: var(--font-mono); font-weight: 600;
  color: var(--zinc-100); margin-left: 12px; font-size: 1rem;
}
.chrome .meta {
  margin-left: auto; font-family: var(--font-mono);
  color: var(--zinc-300); font-size: 0.85rem;
}
.chrome .back {
  color: var(--zinc-400); text-decoration: none;
  font-family: var(--font-mono); font-size: 0.85rem;
  padding: 4px 10px; border-radius: 6px;
  border: 1px solid rgba(63,63,70,0.6);
  transition: color 0.18s, border-color 0.18s;
  margin-left: auto;
}
.chrome .back:hover { color: var(--syntax-keyword); border-color: var(--syntax-keyword); }
@media (max-width: 640px) { .chrome .meta { display: none; } }

#progress-bar {
  position: fixed; top: 0; left: 0; height: 3px; width: 0%;
  background: linear-gradient(90deg, var(--syntax-keyword), var(--syntax-fn));
  z-index: 300; transition: width 0.1s linear;
}

#side-nav {
  position: fixed; right: 18px; top: 50%; transform: translateY(-50%);
  z-index: 150; display: flex; flex-direction: column; gap: 10px;
}
#side-nav a {
  width: 12px; height: 12px; border-radius: 50%;
  background: rgba(255,255,255,0.12); border: 1px solid rgba(255,255,255,0.18);
  position: relative;
}
#side-nav a[data-label]:hover::after {
  content: attr(data-label);
  position: absolute; right: 22px; top: 50%; transform: translateY(-50%);
  background: rgba(15,20,25,0.95); color: var(--zinc-200);
  padding: 4px 8px; border-radius: 6px; font-size: 0.75rem;
  white-space: nowrap; font-family: var(--font-mono);
}
#side-nav a.active {
  background: var(--syntax-keyword); border-color: var(--syntax-keyword);
  box-shadow: 0 0 0 4px rgba(130,170,255,0.18);
}
@media (max-width: 900px) { #side-nav { display: none; } }

main { display: block; position: relative; z-index: 10; }

/* Sections */
.section {
  padding: 70px 24px;
  display: flex; justify-content: center;
}
.container {
  width: 100%; max-width: 900px;
  background: rgba(26,31,46,0.72);
  backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
  border: 1px solid rgba(63,63,70,0.6);
  border-radius: 12px;
  padding: 32px 34px;
}
.section.hero .container {
  background: transparent; border: none; padding: 0;
  backdrop-filter: none; -webkit-backdrop-filter: none;
  max-width: 900px;
}

.hero { min-height: 78vh; align-items: center; }
.hero-inner {
  text-align: left; max-width: 820px; width: 100%;
  background: rgba(26,31,46,0.72);
  backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
  border: 1px solid rgba(63,63,70,0.6);
  border-radius: 14px;
  padding: 40px 40px 32px;
  position: relative; overflow: hidden;
}
.hero-inner::after {
  content: ""; position: absolute; top: -60px; right: -60px;
  width: 260px; height: 260px; border-radius: 50%;
  background: radial-gradient(circle, rgba(130,170,255,0.18), transparent 70%);
  pointer-events: none;
}
.eyebrow {
  font-family: var(--font-mono);
  font-size: 0.75rem; letter-spacing: 0.15em; text-transform: uppercase;
  color: var(--syntax-keyword); margin: 0 0 14px;
}
.hero h1 {
  font-family: var(--font-sans);
  font-size: clamp(2.2rem, 5vw, 3.4rem);
  margin: 0 0 22px; letter-spacing: -0.02em; line-height: 1.05;
  color: var(--zinc-50);
}
.hero h1 .accent { color: var(--syntax-fn); }
.scroll-cue {
  display: inline-block; color: var(--zinc-300); text-decoration: none;
  margin-top: 12px; padding: 8px 14px;
  border: 1px solid rgba(63,63,70,0.7);
  border-radius: 999px;
  font-family: var(--font-mono); font-size: 0.85rem;
  transition: color 0.2s, border-color 0.2s;
}
.scroll-cue:hover { color: var(--syntax-keyword); border-color: var(--syntax-keyword); }

/* Typography */
h2 {
  font-size: clamp(1.5rem, 3vw, 2rem);
  margin: 0 0 12px; letter-spacing: -0.01em;
  color: var(--zinc-50);
}
h3 { font-size: 1.15rem; margin: 22px 0 8px; color: var(--zinc-100); }
h4 { font-size: 1rem; margin: 16px 0 6px; color: var(--zinc-100); }
p { margin: 8px 0; color: var(--zinc-200); }
p.sub { color: var(--zinc-400); margin: 0 0 20px; font-size: 1rem; }
strong { color: var(--zinc-50); }
em { color: var(--syntax-string); font-style: normal; }
ul, ol { padding-left: 22px; color: var(--zinc-200); }
li { margin: 6px 0; }

.section-tag {
  font-family: var(--font-mono);
  font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.15em;
  color: var(--zinc-300); margin: 0 0 12px;
}
.section-tag::before { content: "// "; color: var(--syntax-comment); }

/* Callouts */
.callout {
  background: rgba(22,27,34,0.85);
  border: 1px solid rgba(63,63,70,0.6);
  border-left: 4px solid var(--syntax-keyword);
  border-radius: 8px;
  padding: 16px 20px; margin: 18px 0;
  color: var(--zinc-200);
}
.callout.tip { border-left-color: var(--syntax-fn); }
.callout.tip .title { color: var(--syntax-fn); }
.callout.warn { border-left-color: var(--syntax-const); }
.callout.warn .title { color: var(--syntax-const); }
.callout.example { border-left-color: var(--green); background: rgba(74,222,128,0.05); }
.callout.example .title { color: var(--green); }
.callout .title {
  font-family: var(--font-mono);
  font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.1em;
  color: var(--syntax-keyword); margin: 0 0 6px;
  font-weight: 600;
}

.objectives-list { padding-left: 22px; color: var(--zinc-200); }
.objectives-list li { margin: 6px 0; }
.objectives-list li strong { color: var(--syntax-fn); }

/* ====================== TABLES ====================== */
table.data {
  width: 100%; border-collapse: collapse;
  margin: 14px 0;
  font-family: var(--font-mono); font-size: 0.85rem;
  background: rgba(15,20,25,0.55);
  border-radius: 8px;
  overflow: hidden;
}
table.data th, table.data td {
  border: 1px solid rgba(63,63,70,0.5);
  padding: 8px 12px; text-align: left;
  color: var(--zinc-200);
}
table.data th {
  background: rgba(130,170,255,0.12);
  color: var(--syntax-keyword);
  font-weight: 600;
}
table.data td strong { color: var(--syntax-fn); }

/* ============ INTERACTIVE: FLIP CARDS ============ */
.flip-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 14px; margin: 16px 0;
}
.flip-card {
  background: none; border: none; padding: 0;
  perspective: 1000px; cursor: pointer;
  min-height: 130px;
  font-family: inherit;
}
.flip-card .inner {
  position: relative; width: 100%; min-height: 130px;
  transition: transform 0.6s;
  transform-style: preserve-3d;
}
.flip-card.flipped .inner { transform: rotateY(180deg); }
.flip-card .face {
  position: absolute; inset: 0;
  backface-visibility: hidden;
  border: 1px solid rgba(63,63,70,0.7);
  border-radius: 10px;
  padding: 16px;
  display: flex; flex-direction: column; justify-content: center; align-items: center;
  text-align: center;
  background: rgba(26,31,46,0.85);
}
.flip-card .face.back {
  transform: rotateY(180deg);
  background: rgba(130,170,255,0.12);
  border-color: rgba(130,170,255,0.4);
}
.flip-card .face h4 { margin: 0 0 6px; color: var(--zinc-50); font-size: 0.95rem; }
.flip-card .face p { margin: 0; font-size: 0.85rem; color: var(--zinc-300); }
.flip-card .face .hint {
  font-family: var(--font-mono); font-size: 0.7rem;
  color: var(--syntax-comment); margin-top: 6px;
}

/* ============ INTERACTIVE: REVEAL ============ */
.reveal-block {
  background: rgba(15,20,25,0.55);
  border: 1px dashed rgba(130,170,255,0.35);
  border-radius: 8px;
  padding: 14px 16px; margin: 12px 0;
}
.reveal-block .q { font-weight: 500; color: var(--zinc-100); margin: 0 0 8px; }
.reveal-block button.reveal-btn {
  background: rgba(130,170,255,0.15);
  color: var(--syntax-keyword);
  border: 1px solid rgba(130,170,255,0.3);
  border-radius: 6px;
  padding: 6px 14px;
  font-family: var(--font-mono); font-size: 0.85rem;
  cursor: pointer;
  transition: background 0.18s;
}
.reveal-block button.reveal-btn:hover { background: rgba(130,170,255,0.25); }
.reveal-block .answer {
  margin-top: 10px; padding: 10px 12px;
  background: rgba(74,222,128,0.08);
  border-left: 3px solid var(--green);
  border-radius: 4px;
  color: var(--zinc-100);
}
.reveal-block .answer[hidden] { display: none; }

/* ============ BUTTONS ============ */
button.btn {
  background: rgba(130,170,255,0.18);
  color: var(--syntax-keyword);
  border: 1px solid rgba(130,170,255,0.35);
  border-radius: 6px;
  padding: 8px 16px;
  font-family: var(--font-mono); font-size: 0.85rem;
  cursor: pointer;
  transition: background 0.18s, transform 0.1s;
}
button.btn:hover { background: rgba(130,170,255,0.28); }
button.btn:active { transform: scale(0.97); }
button.btn.ghost { background: transparent; }
button.btn.warn { background: rgba(248,113,113,0.18); color: var(--red); border-color: rgba(248,113,113,0.4); }
button.btn.warn:hover { background: rgba(248,113,113,0.28); }

/* ============ BINARY BIT ROW ============ */
.bit-row {
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  gap: 6px;
  margin: 10px 0;
}
.bit-row .bit {
  aspect-ratio: 1;
  display: flex; align-items: center; justify-content: center;
  flex-direction: column;
  background: rgba(15,20,25,0.7);
  border: 1px solid rgba(63,63,70,0.7);
  border-radius: 6px;
  font-family: var(--font-mono);
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s, transform 0.1s;
  user-select: none;
}
.bit-row .bit .place {
  font-size: 0.65rem; color: var(--syntax-comment);
  margin-bottom: 2px;
}
.bit-row .bit .val {
  font-size: 1.3rem; font-weight: 700;
  color: var(--zinc-300);
}
.bit-row .bit.on {
  background: rgba(130,170,255,0.22);
  border-color: var(--syntax-keyword);
}
.bit-row .bit.on .val { color: var(--syntax-keyword); }
.bit-row .bit:hover { transform: translateY(-2px); border-color: var(--syntax-keyword); }
.bit-row .bit:active { transform: translateY(0); }
.bit-row.readonly .bit { cursor: default; }
.bit-row.readonly .bit:hover { transform: none; border-color: rgba(63,63,70,0.7); }
.bit-row.readonly .bit.on:hover { border-color: var(--syntax-keyword); }

.bit-display {
  display: flex; align-items: center; justify-content: space-between;
  gap: 12px; padding: 10px 14px;
  background: rgba(15,20,25,0.7);
  border: 1px solid rgba(63,63,70,0.6);
  border-radius: 8px;
  margin: 10px 0;
  font-family: var(--font-mono);
}
.bit-display .lbl { color: var(--zinc-400); font-size: 0.8rem; }
.bit-display .val {
  font-size: 1.15rem; color: var(--syntax-fn); font-weight: 700;
}

/* ============ HEX NIBBLES ============ */
.nibble-row {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 6px;
}

/* ============ PIXEL GRID (images topic) ============ */
.pixel-grid {
  display: grid;
  gap: 1px;
  background: rgba(63,63,70,0.5);
  padding: 1px; border-radius: 4px;
  margin: 10px auto;
  max-width: 100%;
}
.pixel-grid .px {
  aspect-ratio: 1;
  cursor: pointer;
  transition: transform 0.08s;
  background: #000;
}
.pixel-grid .px:hover { transform: scale(1.15); z-index: 2; }

/* ============ ASCII TABLE ============ */
.ascii-explorer {
  display: grid; grid-template-columns: 1fr 1fr; gap: 20px;
  margin: 14px 0;
}
@media (max-width: 640px) { .ascii-explorer { grid-template-columns: 1fr; } }
.ascii-explorer .side {
  background: rgba(15,20,25,0.55);
  border: 1px solid rgba(63,63,70,0.6);
  border-radius: 8px;
  padding: 16px;
}
.ascii-explorer input {
  width: 100%; padding: 8px 12px;
  background: rgba(0,0,0,0.4);
  border: 1px solid rgba(63,63,70,0.7);
  border-radius: 6px;
  color: var(--zinc-100);
  font-family: var(--font-mono); font-size: 1rem;
}
.ascii-explorer .result {
  margin-top: 10px; font-family: var(--font-mono);
  font-size: 0.9rem; line-height: 1.8;
}
.ascii-explorer .result .k { color: var(--zinc-400); }
.ascii-explorer .result .v { color: var(--syntax-fn); font-weight: 600; }
.ascii-explorer .result .b { color: var(--syntax-string); }

/* ============ SLIDERS ============ */
.slider-row {
  display: flex; align-items: center; gap: 14px;
  margin: 10px 0;
}
.slider-row label {
  font-family: var(--font-mono); font-size: 0.85rem;
  color: var(--zinc-300); min-width: 100px;
}
.slider-row input[type="range"] {
  flex: 1;
  accent-color: var(--syntax-keyword);
}
.slider-row .val {
  font-family: var(--font-mono);
  color: var(--syntax-fn); font-weight: 700;
  min-width: 90px; text-align: right;
}

/* ============ COMPRESSION SLIDER ============ */
.comp-viewer {
  position: relative; width: 100%;
  max-width: 500px; margin: 10px auto;
  border-radius: 8px; overflow: hidden;
  background: rgba(0,0,0,0.3);
  border: 1px solid rgba(63,63,70,0.6);
  aspect-ratio: 4 / 3;
}
.comp-viewer .layer {
  position: absolute; inset: 0;
  display: flex; align-items: center; justify-content: center;
  font-family: var(--font-mono);
  color: var(--zinc-100);
  transition: filter 0.2s;
}
.comp-viewer .layer.orig { background: linear-gradient(135deg, #8b7355, #4a3a2a, #d4a373, #2a1a0f); }
.comp-viewer .info {
  position: absolute; bottom: 10px; left: 10px;
  background: rgba(0,0,0,0.7); padding: 6px 10px; border-radius: 6px;
  font-family: var(--font-mono); font-size: 0.8rem;
  color: var(--zinc-100);
}

/* ============ ADDITION CALCULATOR ============ */
.add-grid {
  display: grid; gap: 4px;
  margin: 14px 0;
  font-family: var(--font-mono);
  overflow-x: auto;
  padding-bottom: 4px;
}
.add-grid .row {
  display: grid;
  grid-template-columns: 36px repeat(var(--cols, 8), minmax(38px, 1fr));
  gap: 4px;
  align-items: stretch;
  min-width: max-content;
}
.add-grid .row .lbl {
  display: flex; align-items: center; justify-content: flex-end;
  color: var(--zinc-400); font-size: 0.85rem;
  padding-right: 6px;
  min-width: 30px;
}
.add-grid .row .cell {
  height: 40px;
  display: flex; align-items: center; justify-content: center;
  background: rgba(15,20,25,0.6);
  border: 1px solid rgba(63,63,70,0.5);
  border-radius: 4px;
  color: var(--zinc-100);
  font-weight: 600;
  font-size: 0.95rem;
}
.add-grid .row.header .cell {
  background: rgba(130,170,255,0.12);
  color: var(--syntax-keyword);
  font-size: 0.8rem;
  height: 32px;
}
.add-grid .row .cell.result { background: rgba(74,222,128,0.12); color: var(--green); border-color: rgba(74,222,128,0.4); }
.add-grid .row .cell.carry { background: rgba(251,191,36,0.15); color: var(--amber); border-color: rgba(251,191,36,0.4); }
.add-grid .row .cell.overflow { background: rgba(248,113,113,0.18); color: var(--red); border-color: rgba(248,113,113,0.5); }

/* ============ WAVE / SAMPLING ============ */
.wave-box {
  background: rgba(15,20,25,0.6);
  border: 1px solid rgba(63,63,70,0.6);
  border-radius: 8px;
  padding: 14px;
  margin: 10px 0;
}
.wave-box canvas { display: block; width: 100%; height: 180px; }

/* ============ COLOUR DEPTH DEMO ============ */
.depth-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 10px; margin: 12px 0;
}
.depth-swatch {
  display: flex; flex-direction: column; align-items: center;
  padding: 10px 6px;
  border: 1px solid rgba(63,63,70,0.6);
  border-radius: 8px;
  background: rgba(15,20,25,0.6);
  font-family: var(--font-mono); font-size: 0.75rem;
  color: var(--zinc-300);
}
.depth-swatch .sample {
  width: 100%; height: 50px; border-radius: 4px;
  margin-bottom: 6px;
}
.depth-swatch strong { color: var(--syntax-fn); font-size: 0.85rem; }

/* ============ COLOUR PICKER (hex) ============ */
.hex-picker {
  display: grid; grid-template-columns: 1fr 1fr; gap: 20px;
  align-items: center;
  padding: 16px; background: rgba(15,20,25,0.55);
  border: 1px solid rgba(63,63,70,0.6);
  border-radius: 8px;
  margin: 12px 0;
}
@media (max-width: 640px) { .hex-picker { grid-template-columns: 1fr; } }
.hex-picker .swatch { width: 100%; aspect-ratio: 1; border-radius: 8px; border: 1px solid rgba(63,63,70,0.6); }
.hex-picker .controls label { font-family: var(--font-mono); font-size: 0.85rem; color: var(--zinc-300); display: block; margin: 6px 0 2px; }
.hex-picker .controls input {
  width: 100%; padding: 6px 10px;
  background: rgba(0,0,0,0.4);
  border: 1px solid rgba(63,63,70,0.7);
  border-radius: 6px;
  color: var(--zinc-100); font-family: var(--font-mono);
}
.hex-picker .hex-out {
  font-family: var(--font-mono); font-size: 1.4rem;
  color: var(--syntax-string); text-align: center;
  padding: 8px; background: rgba(0,0,0,0.4); border-radius: 6px;
  margin-top: 10px;
}

/* ============ TOPIC NAVIGATION ============ */
.topic-nav {
  position: relative; z-index: 10;
  max-width: 900px;
  margin: 16px auto;
  padding: 14px 18px;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  background: rgba(26,31,46,0.72);
  backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
  border: 1px solid rgba(63,63,70,0.6);
  border-radius: 12px;
  font-family: var(--font-mono); font-size: 0.9rem;
}
.topic-nav a {
  padding: 10px 16px;
  border-radius: 8px;
  border: 1px solid rgba(63,63,70,0.6);
  color: var(--zinc-200);
  text-decoration: none;
  background: rgba(15,20,25,0.55);
  transition: border-color 0.15s, color 0.15s, background 0.15s, transform 0.1s;
  display: flex; align-items: center; gap: 6px;
}
.topic-nav a:hover {
  border-color: var(--syntax-keyword);
  color: var(--syntax-keyword);
  background: rgba(130,170,255,0.10);
  transform: translateY(-1px);
}
.topic-nav .prev { justify-content: flex-start; }
.topic-nav .hub {
  justify-content: center;
  border-color: rgba(130,170,255,0.35);
  background: rgba(130,170,255,0.10);
  color: var(--syntax-keyword);
  font-weight: 600;
}
.topic-nav .hub:hover {
  background: rgba(130,170,255,0.20);
}
.topic-nav .next { justify-content: flex-end; }
.topic-nav .placeholder-cell {
  padding: 10px 16px;
  color: var(--zinc-600);
  border: 1px dashed rgba(63,63,70,0.4);
  border-radius: 8px;
  background: transparent;
  display: flex; align-items: center;
}
.topic-nav .prev.placeholder-cell { justify-content: flex-start; }
.topic-nav .next.placeholder-cell { justify-content: flex-end; }
@media (max-width: 640px) {
  .topic-nav {
    grid-template-columns: 1fr;
    gap: 8px;
  }
  .topic-nav .prev, .topic-nav .next, .topic-nav .hub {
    justify-content: center;
  }
}

/* ============ END ============ */
.end-note {
  text-align: center; color: var(--zinc-500);
  padding: 30px 0 60px; font-size: 0.85rem;
  font-family: var(--font-mono);
  position: relative; z-index: 10;
}

.placeholder {
  border: 2px dashed rgba(63,63,70,0.7);
  border-radius: 12px;
  padding: 28px 24px;
  color: var(--zinc-400);
  font-family: var(--font-mono);
  font-size: 0.9rem;
  text-align: center;
  background: rgba(22,27,34,0.5);
}
.placeholder strong { color: var(--zinc-100); }

/* ==================================================================
   RICHER DEMOS — mosaic, zoom, pixel art, quiz, calculator, playback
   ================================================================== */

/* Two-column layout */
.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  align-items: start;
}
@media (max-width: 720px) {
  .two-col { grid-template-columns: 1fr; }
}
.two-col figure { margin: 0; }
.two-col figcaption {
  font-family: var(--font-mono); font-size: 0.8rem;
  color: var(--zinc-400); text-align: center; margin-top: 6px;
}

/* Canvas shells */
.mosaic-demo canvas,
.pixel-art canvas {
  display: block;
  width: 100%; max-width: 360px;
  height: auto;
  background: #0b0f14;
  border: 1px solid rgba(63,63,70,0.6);
  border-radius: 10px;
  image-rendering: pixelated;
  image-rendering: -moz-crisp-edges;
  image-rendering: crisp-edges;
}
.zoom-stage canvas,
.res-figure canvas,
.depth-figure canvas {
  display: block;
  width: 100%; max-width: 480px;
  height: auto;
  background: #0b0f14;
  border: 1px solid rgba(63,63,70,0.6);
  border-radius: 10px;
  image-rendering: pixelated;
  image-rendering: -moz-crisp-edges;
  image-rendering: crisp-edges;
}

/* Colour → binary mini table */
table.colour-binary-table {
  width: 100%; border-collapse: collapse;
  margin: 14px 0;
  font-family: var(--font-mono); font-size: 0.85rem;
  background: rgba(15,20,25,0.55);
  border-radius: 8px; overflow: hidden;
}
table.colour-binary-table th,
table.colour-binary-table td {
  border: 1px solid rgba(63,63,70,0.5);
  padding: 6px 10px; text-align: left; color: var(--zinc-200);
}
table.colour-binary-table th {
  background: rgba(130,170,255,0.12);
  color: var(--syntax-keyword); font-weight: 600;
}
table.colour-binary-table td code {
  color: var(--syntax-string); background: rgba(0,0,0,0.35);
  padding: 1px 6px; border-radius: 3px;
}
.swatch-box {
  display: inline-block;
  width: 22px; height: 22px;
  border-radius: 4px;
  vertical-align: middle;
  border: 1px solid rgba(63,63,70,0.6);
}

.hint {
  font-family: var(--font-mono); font-size: 0.85rem;
  color: var(--zinc-400); margin-top: 10px;
}

/* Formula block */
.formula {
  background: rgba(74,222,128,0.06);
  border: 1px solid rgba(74,222,128,0.35);
  border-radius: 8px;
  padding: 14px 18px;
  margin: 14px 0;
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--syntax-string);
  text-align: center;
}

/* Controls (slider row + label) */
.controls {
  background: rgba(15,20,25,0.55);
  border: 1px solid rgba(63,63,70,0.6);
  border-radius: 8px;
  padding: 14px 16px;
  margin: 12px 0;
}
.controls label {
  font-family: var(--font-mono); font-size: 0.85rem;
  color: var(--zinc-300); display: block; margin-bottom: 8px;
}
.controls output {
  color: var(--syntax-fn); font-weight: 700; margin-left: 6px;
}
.controls input[type="range"] {
  width: 100%; accent-color: var(--syntax-keyword);
}
.controls.wide { margin-top: 16px; }

/* Zoom stage */
.zoom-demo { display: block; }
.zoom-stage { display: flex; justify-content: center; margin-bottom: 12px; }

/* Pixel art */
.pixel-art {
  display: flex; flex-direction: column; align-items: center;
  gap: 12px;
  margin-top: 16px;
}
.palette {
  display: flex; gap: 8px; flex-wrap: wrap; justify-content: center;
}
.palette .swatch {
  width: 34px; height: 34px;
  border-radius: 6px;
  border: 2px solid rgba(63,63,70,0.6);
  cursor: pointer;
  padding: 0;
  transition: transform 0.1s, border-color 0.15s;
  display: flex; align-items: center; justify-content: center;
  color: rgba(0,0,0,0.6); font-weight: 700;
}
.palette .swatch:hover { transform: translateY(-2px); }
.palette .swatch.active {
  border-color: var(--syntax-keyword);
  box-shadow: 0 0 0 3px rgba(130,170,255,0.25);
}
#pixelArt { max-width: 360px; cursor: crosshair; background: #ffffff; }

/* Colour depth / resolution figures */
.depth-table {
  width: 100%; border-collapse: collapse;
  font-family: var(--font-mono); font-size: 0.85rem;
  margin: 10px 0;
}
.depth-table th, .depth-table td {
  border: 1px solid rgba(63,63,70,0.5);
  padding: 6px 10px; text-align: left; color: var(--zinc-200);
}
.depth-table th {
  background: rgba(130,170,255,0.12);
  color: var(--syntax-keyword); font-weight: 600;
}

/* File-size calculator */
.calc {
  background: rgba(15,20,25,0.55);
  border: 1px solid rgba(63,63,70,0.6);
  border-radius: 10px;
  padding: 16px 18px;
  margin: 14px 0;
}
.calc-inputs {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 12px 16px;
}
.calc-inputs label {
  font-family: var(--font-mono); font-size: 0.8rem;
  color: var(--zinc-300); display: block;
}
.calc-inputs input,
.calc-inputs select {
  width: 100%; margin-top: 4px;
  padding: 8px 10px;
  background: rgba(0,0,0,0.4);
  border: 1px solid rgba(63,63,70,0.7);
  border-radius: 6px;
  color: var(--zinc-100);
  font-family: var(--font-mono); font-size: 0.9rem;
}
.calc-output {
  margin-top: 14px;
  padding: 12px 14px;
  background: rgba(0,0,0,0.35);
  border-left: 3px solid var(--syntax-fn);
  border-radius: 6px;
  font-family: var(--font-mono); font-size: 0.9rem;
  color: var(--zinc-100);
}
.calc-output p { margin: 4px 0; }
.calc-output strong { color: var(--syntax-fn); }

/* Play buttons for sound */
.play-cluster {
  display: flex; gap: 10px; flex-wrap: wrap; margin: 12px 0;
}
.play-btn {
  background: rgba(130,170,255,0.18);
  color: var(--syntax-keyword);
  border: 1px solid rgba(130,170,255,0.35);
  border-radius: 999px;
  padding: 10px 18px;
  font-family: var(--font-mono); font-size: 0.9rem; font-weight: 600;
  cursor: pointer;
  transition: background 0.15s, transform 0.1s;
  display: inline-flex; align-items: center; gap: 8px;
}
.play-btn:hover { background: rgba(130,170,255,0.28); }
.play-btn:active { transform: scale(0.96); }
.play-btn:disabled { opacity: 0.5; cursor: default; }
.play-btn.warn { background: rgba(248,113,113,0.18); color: var(--red); border-color: rgba(248,113,113,0.4); }
.play-btn.good { background: rgba(74,222,128,0.15); color: var(--green); border-color: rgba(74,222,128,0.4); }

.play-status {
  font-family: var(--font-mono); font-size: 0.85rem;
  color: var(--zinc-400); margin: 6px 0 0;
}

/* Sound-source picker pills */
.sound-picker {
  display: flex; flex-wrap: wrap; gap: 8px;
  margin: 10px 0 18px;
}
.sound-picker .pick-btn {
  background: rgba(15,20,25,0.7);
  color: var(--zinc-200);
  border: 1px solid rgba(63,63,70,0.7);
  border-radius: 999px;
  padding: 8px 16px;
  font-family: var(--font-mono); font-size: 0.85rem;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s, color 0.15s;
}
.sound-picker .pick-btn:hover {
  border-color: var(--syntax-keyword);
  color: var(--zinc-50);
}
.sound-picker .pick-btn.active {
  background: rgba(130,170,255,0.18);
  border-color: var(--syntax-keyword);
  color: var(--syntax-keyword);
}

/* Quiz */
.quiz {
  background: rgba(15,20,25,0.55);
  border: 1px solid rgba(63,63,70,0.6);
  border-radius: 10px;
  padding: 20px 22px;
  margin: 14px 0;
}
.quiz ol {
  list-style: none; padding: 0; margin: 0;
  counter-reset: quiz;
}
.quiz li {
  margin-bottom: 22px;
  padding-bottom: 18px;
  border-bottom: 1px dashed rgba(63,63,70,0.5);
}
.quiz li:last-of-type { border-bottom: none; padding-bottom: 0; }
.quiz li p { color: var(--zinc-100); margin: 0 0 8px; }
.quiz label {
  display: block;
  padding: 8px 12px;
  margin: 6px 0;
  background: rgba(0,0,0,0.35);
  border: 1px solid rgba(63,63,70,0.6);
  border-radius: 6px;
  color: var(--zinc-200);
  font-size: 0.95rem;
  cursor: pointer;
  transition: border-color 0.15s, background 0.15s;
}
.quiz label:hover { border-color: var(--syntax-keyword); }
.quiz label input[type="radio"] {
  margin-right: 10px; accent-color: var(--syntax-keyword);
}
.quiz-result {
  margin-top: 14px;
  padding: 12px 14px;
  border-radius: 6px;
  font-family: var(--font-mono); font-size: 0.9rem;
  color: var(--zinc-100);
}
.quiz-result.good {
  background: rgba(74,222,128,0.12);
  border-left: 3px solid var(--green);
}
.quiz-result.bad {
  background: rgba(248,113,113,0.10);
  border-left: 3px solid var(--red);
}
.quiz-result strong { color: var(--syntax-fn); }
.quiz-summary {
  margin-top: 22px;
  background: rgba(74,222,128,0.06);
  border: 1px solid rgba(74,222,128,0.35);
  border-radius: 10px;
  padding: 16px 20px;
}
.quiz-summary h3 { margin: 0 0 10px; color: var(--green); }
.quiz-summary ul { margin: 6px 0 0 20px; }