/* entropy-style.css — shared 3Blue1Brown dark theme for entropy lecture guides */

:root {
  --paper: #000000;
  --paper-dark: #000000;
  --ink: #f0f0f5;
  --ink-light: #a0a0b8;
  --accent: #58c4dd;
  --accent-soft: #7fd4e8;
  --accent-warm: #fc6255;
  --accent-yellow: #f5d742;
  --accent-green: #83c167;
  --accent-purple: #9d70d1;
  --highlight: rgba(88, 196, 221, 0.12);
  --grid: rgba(240, 240, 245, 0.035);
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  background: var(--paper-dark);
}

body {
  margin: 0;
  font-family: "Noto Serif SC", "Noto Serif", "STSong", "SimSun", serif;
  color: var(--ink);
  font-size: 18px;
  line-height: 1.85;
  background: var(--paper);
  background-image:
    linear-gradient(90deg, var(--grid) 1px, transparent 1px),
    linear-gradient(var(--grid) 1px, transparent 1px);
  background-size: 32px 32px;
  min-height: 100vh;
}

.page {
  max-width: 1040px;
  margin: 0 auto;
  padding: 64px 72px 120px;
  background: var(--paper);
  border-left: 1px solid rgba(240, 240, 245, 0.06);
  border-right: 1px solid rgba(240, 240, 245, 0.06);
  box-shadow: 0 0 80px rgba(88, 196, 221, 0.04), 0 0 40px rgba(0, 0, 0, 0.5);
  min-height: 100vh;
  position: relative;
}

.binding {
  position: fixed;
  left: 50%;
  top: 0;
  transform: translateX(-520px);
  width: 3px;
  height: 100vh;
  background: linear-gradient(180deg, transparent 0%, rgba(88, 196, 221, 0.2) 8%, rgba(88, 196, 221, 0.2) 92%, transparent 100%);
  pointer-events: none;
}

header {
  border-bottom: 2px solid var(--ink);
  padding-bottom: 32px;
  margin-bottom: 40px;
  position: relative;
}

.course-label {
  display: inline-block;
  font-family: "Caveat", cursive;
  font-size: 1.3rem;
  color: var(--accent);
  transform: rotate(-2deg);
  margin-bottom: 8px;
}

h1 {
  font-size: 2.8rem;
  line-height: 1.2;
  margin: 0 0 16px 0;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.meta {
  font-size: 0.95rem;
  color: var(--ink-light);
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
}

.meta span { border-bottom: 1px dotted var(--ink-light); padding-bottom: 2px; }

h2 {
  font-size: 1.45rem;
  margin: 48px 0 20px;
  padding-left: 16px;
  border-left: 5px solid var(--accent);
  line-height: 1.35;
}

h3 {
  font-size: 1.15rem;
  margin: 32px 0 12px;
  color: var(--ink);
  font-weight: 700;
}

p { margin: 0 0 16px; }

details {
  margin: 16px 0;
  border: 1px solid rgba(240, 240, 245, 0.12);
  border-radius: 3px;
  background: rgba(255, 255, 255, 0.03);
  overflow: hidden;
}

summary {
  padding: 16px 20px;
  cursor: pointer;
  font-weight: 600;
  list-style: none;
  position: relative;
  transition: background 0.2s ease;
}

summary:hover { background: rgba(88, 196, 221, 0.08); }

summary::-webkit-details-marker { display: none; }

summary::after {
  content: "+";
  position: absolute;
  right: 20px;
  top: 50%;
  transform: translateY(-50%);
  font-family: "Noto Serif", serif;
  font-size: 1.4rem;
  color: var(--accent);
  transition: transform 0.25s ease;
}

details[open] summary::after { transform: translateY(-50%) rotate(45deg); }

.detail-body { padding: 4px 20px 20px; }

.sidenote {
  float: right;
  clear: right;
  width: 180px;
  margin: 0 -200px 16px 24px;
  padding: 10px 14px;
  font-family: "Caveat", cursive;
  font-size: 1.1rem;
  line-height: 1.4;
  color: var(--accent-green);
  border-top: 2px solid var(--accent-green);
  background: rgba(131, 193, 103, 0.07);
  transform: rotate(1deg);
}

.figure {
  margin: 28px 0;
  padding: 20px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid rgba(240, 240, 245, 0.1);
  border-radius: 3px;
  text-align: center;
}

.figure canvas {
  width: 100%;
  max-width: 880px;
  height: auto;
  display: block;
  margin: 0 auto;
}

.figure-caption {
  font-size: 0.85rem;
  color: var(--ink-light);
  margin-top: 12px;
  font-style: italic;
}

.callout {
  margin: 24px 0;
  padding: 18px 22px;
  background: var(--highlight);
  border-left: 4px solid var(--accent);
  border-radius: 0 3px 3px 0;
}

.callout strong { color: var(--accent); }

.term {
  display: inline-block;
  padding: 1px 8px;
  background: rgba(88, 196, 221, 0.15);
  border-radius: 2px;
  font-size: 0.92em;
  font-weight: 600;
  color: var(--accent);
  margin: 0 2px;
}

.compare {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin: 24px 0;
}

.compare-card {
  padding: 18px;
  background: rgba(255, 255, 255, 0.03);
  border: 1.5px solid rgba(240, 240, 245, 0.1);
  border-radius: 3px;
}

.compare-card h4 {
  margin: 0 0 10px;
  font-size: 1rem;
  color: var(--accent-warm);
}

.code-block {
  font-family: "Fira Code", "SF Mono", monospace;
  font-size: 0.9em;
  background: rgba(0, 0, 0, 0.25);
  padding: 14px 18px;
  border-radius: 3px;
  border-left: 3px solid var(--accent-yellow);
  margin: 16px 0;
  overflow-x: auto;
}

.controls {
  display: flex;
  gap: 16px;
  align-items: stretch;
  justify-content: center;
  margin: 20px 0 8px;
  flex-wrap: wrap;
}

.control-group {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
  color: var(--ink-light);
  min-height: 36px;
  padding: 4px 0;
}

.control-group label {
  white-space: nowrap;
  line-height: 1.2;
}

.control-group span {
  min-width: 48px;
  text-align: right;
}

input[type="range"] {
  accent-color: var(--accent);
  height: 20px;
  margin: 0;
  vertical-align: middle;
}

.legend {
  display: flex;
  gap: 16px;
  justify-content: center;
  margin-top: 12px;
  font-size: 0.85rem;
  color: var(--ink-light);
}

.legend span { display: inline-flex; align-items: center; gap: 6px; }
.legend i { width: 12px; height: 12px; border-radius: 2px; display: inline-block; }

.stats-bar {
  margin: 16px auto 4px;
  padding: 14px 24px;
  display: inline-block;
  background: rgba(88, 196, 221, 0.08);
  border: 1px solid rgba(88, 196, 221, 0.25);
  border-radius: 3px;
  font-family: "Fira Code", "SF Mono", monospace;
  font-size: 0.95rem;
  color: var(--ink-light);
}

.stats-bar strong {
  color: var(--accent);
  font-weight: 600;
}

/* Navigation */
.nav-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-top: 64px;
  padding-top: 32px;
  border-top: 1px solid rgba(240, 240, 245, 0.12);
}

.nav-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 22px;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--ink);
  text-decoration: none;
  background: rgba(88, 196, 221, 0.08);
  border: 1px solid rgba(88, 196, 221, 0.3);
  border-radius: 3px;
  transition: background 0.2s ease, border-color 0.2s ease;
}

.nav-btn:hover {
  background: rgba(88, 196, 221, 0.16);
  border-color: var(--accent);
}

.nav-btn.disabled {
  pointer-events: none;
  color: var(--ink-light);
  background: rgba(255, 255, 255, 0.03);
  border-color: rgba(240, 240, 245, 0.1);
}

.progress {
  font-family: "Fira Code", "SF Mono", monospace;
  font-size: 0.9rem;
  color: var(--ink-light);
}

/* Course contents grid */
.contents-section {
  margin: 32px 0 48px;
}

.contents-header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  margin-bottom: 16px;
}

.contents-title {
  font-size: 1.1rem;
  margin: 0;
  color: var(--ink-light);
  font-weight: 600;
}

.contents-subtitle {
  font-size: 0.85rem;
  color: var(--ink-light);
  font-family: "Caveat", cursive;
}

.contents-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.contents-card {
  display: block;
  padding: 18px;
  background: rgba(255, 255, 255, 0.03);
  border: 1.5px solid rgba(240, 240, 245, 0.1);
  border-radius: 3px;
  text-decoration: none;
  color: inherit;
  transition: background 0.2s ease, border-color 0.2s ease;
}

.contents-card:hover {
  background: rgba(88, 196, 221, 0.06);
  border-color: rgba(88, 196, 221, 0.3);
}

.contents-card.active {
  background: rgba(88, 196, 221, 0.1);
  border-color: var(--accent);
  pointer-events: none;
}

.contents-half-label {
  font-family: "Fira Code", "SF Mono", monospace;
  font-size: 0.75rem;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 8px;
}

.contents-card-title {
  font-size: 1.05rem;
  margin: 0 0 8px;
  color: var(--ink);
}

.contents-card-desc {
  font-size: 0.85rem;
  color: var(--ink-light);
  margin: 0;
  line-height: 1.55;
}