/* ShiClass 课程样式 - 继承 PaperLesson 风格 */

:root {
  --bg: #F7F4EE;
  --card-bg: #FFFFFF;
  --text: #1A1A2E;
  --text-secondary: #5A5A7A;
  --accent: #CC785C;
  --accent-light: #E8A88C;
  --accent-subtle: #F5E6DE;
  --border: #E8E4DC;
  --radius: 12px;
  --shadow: 0 2px 12px rgba(0,0,0,0.06);
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-serif: 'Noto Serif SC', Georgia, serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.8;
  font-size: 16px;
}

.page {
  max-width: 980px;
  margin: 0 auto;
  padding: 0 24px 60px;
}

/* Hero */
.hero {
  padding: 48px 0 32px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 40px;
}

.hero .eyebrow {
  font-size: 0.8rem;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 1px;
  font-weight: 600;
  margin-bottom: 8px;
}

.hero h1 {
  font-family: var(--font-serif);
  font-size: 2rem;
  font-weight: 900;
  line-height: 1.3;
  margin-bottom: 12px;
}

.hero .subtitle {
  font-size: 1.05rem;
  color: var(--text-secondary);
  margin-bottom: 12px;
}

.hero-meta {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.hero-meta span {
  font-size: 0.8rem;
  padding: 3px 12px;
  background: var(--accent-subtle);
  color: var(--accent);
  border-radius: 16px;
  font-weight: 500;
}

/* Lead Grid (双 callout) */
.lead-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-bottom: 32px;
}

@media (max-width: 640px) {
  .lead-grid {
    grid-template-columns: 1fr;
  }
}

/* Section Card */
.section-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 32px;
  margin-bottom: 24px;
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
}

.section-card h2 {
  font-family: var(--font-serif);
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--accent);
}

.section-card h3 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 12px;
  margin-top: 24px;
}

.section-card h3:first-child {
  margin-top: 0;
}

.section-card h4 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--accent);
}

.section-card p {
  margin-bottom: 14px;
}

.section-card p:last-child {
  margin-bottom: 0;
}

/* Callout */
.callout {
  background: var(--accent-subtle);
  border-left: 4px solid var(--accent);
  padding: 16px 20px;
  border-radius: 0 8px 8px 0;
  margin-bottom: 16px;
}

.callout p {
  margin-bottom: 6px;
}

.callout p:last-child {
  margin-bottom: 0;
}

/* Grid */
.grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-bottom: 16px;
}

.grid-3 {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 16px;
  margin-bottom: 16px;
}

@media (max-width: 640px) {
  .grid-2, .grid-3 {
    grid-template-columns: 1fr;
  }
}

/* Mini Card */
.mini-card {
  background: var(--bg);
  border-radius: 8px;
  padding: 16px;
  border: 1px solid var(--border);
}

.mini-card h4 {
  font-size: 0.9rem;
  margin-bottom: 8px;
}

/* Formula Box */
.formula-box {
  background: var(--bg);
  border: 1px dashed var(--accent-light);
  border-radius: 8px;
  padding: 16px 20px;
  margin: 16px 0;
  overflow-x: auto;
  text-align: center;
}

/* Figure */
.figure {
  margin: 20px 0;
  text-align: center;
}

.figure img {
  max-width: 100%;
  border-radius: 8px;
  border: 1px solid var(--border);
}

.figure figcaption {
  margin-top: 8px;
  font-size: 0.85rem;
  color: var(--text-secondary);
  font-style: italic;
}

/* Table */
table {
  width: 100%;
  border-collapse: collapse;
  margin: 16px 0;
  font-size: 0.9rem;
}

th, td {
  padding: 10px 14px;
  border: 1px solid var(--border);
  text-align: left;
}

th {
  background: var(--accent-subtle);
  font-weight: 600;
}

/* Interactive Card */
.interactive-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  margin: 20px 0;
}

.interactive-card h3 {
  margin-top: 0;
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin: 12px 0;
}

.quiz-options button {
  text-align: left;
  padding: 10px 16px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--card-bg);
  cursor: pointer;
  font-size: 0.9rem;
  transition: all 0.2s;
}

.quiz-options button:hover {
  border-color: var(--accent);
  background: var(--accent-subtle);
}

.quiz-options button.correct {
  border-color: #22c55e;
  background: #f0fdf4;
}

.quiz-options button.wrong {
  border-color: #ef4444;
  background: #fef2f2;
}

.quiz-feedback {
  margin-top: 10px;
  padding: 10px 14px;
  border-radius: 8px;
  font-size: 0.9rem;
  display: none;
}

.quiz-feedback.show {
  display: block;
}

.quiz-feedback.correct {
  background: #f0fdf4;
  border: 1px solid #22c55e;
}

.quiz-feedback.wrong {
  background: #fef2f2;
  border: 1px solid #ef4444;
}

/* Exercise Box */
.exercise-box {
  background: var(--card-bg);
  border: 2px solid var(--accent);
  border-radius: var(--radius);
  padding: 24px;
  margin: 24px 0;
}

.exercise-box h3 {
  margin-top: 0;
  color: var(--accent);
}

.exercise-box ol {
  padding-left: 20px;
}

.exercise-box li {
  margin-bottom: 12px;
}

.exercise-answer {
  margin-top: 8px;
  padding: 12px 16px;
  background: var(--bg);
  border-radius: 8px;
}

.exercise-answer summary {
  cursor: pointer;
  font-weight: 500;
  color: var(--accent);
}

.exercise-answer .content {
  margin-top: 8px;
  padding: 8px;
}

/* Navigation */
.nav-links {
  display: flex;
  justify-content: space-between;
  margin-top: 24px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
}

.nav-links a {
  text-decoration: none;
  color: var(--accent);
  font-weight: 500;
  padding: 8px 16px;
  border-radius: 8px;
  transition: all 0.2s;
}

.nav-links a:hover {
  background: var(--accent-subtle);
}

.nav-links a.disabled {
  color: var(--text-secondary);
  opacity: 0.5;
  pointer-events: none;
}

.nav-links a.next {
  margin-left: auto;
}

.foot-note {
  text-align: center;
  margin-top: 20px;
  font-size: 0.85rem;
  color: var(--text-secondary);
}

/* Code */
code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background: var(--bg);
  padding: 2px 6px;
  border-radius: 4px;
}

pre {
  font-family: var(--font-mono);
  background: #1A1A2E;
  color: #E4E4E4;
  padding: 16px;
  border-radius: 8px;
  overflow-x: auto;
  font-size: 0.85rem;
  margin: 16px 0;
}

/* Lists */
ul, ol {
  margin-bottom: 14px;
  padding-left: 24px;
}

li {
  margin-bottom: 6px;
}

/* Summary Grid */
.summary-grid {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 16px;
  margin: 20px 0;
}

@media (max-width: 640px) {
  .summary-grid {
    grid-template-columns: 1fr;
  }
}

/* Flow Formula (centered LaTeX) */
.flow-formula {
  text-align: center;
  padding: 16px 20px;
  margin: 12px 0;
  background: var(--bg);
  border-radius: 8px;
}

/* TOC */
.toc {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 24px;
  margin-bottom: 24px;
}

.toc h3 {
  font-size: 0.9rem;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 10px;
}

.toc ul {
  list-style: none;
  padding: 0;
}

.toc li {
  margin-bottom: 4px;
}

.toc a {
  color: var(--accent);
  text-decoration: none;
  font-size: 0.9rem;
}

.toc a:hover {
  text-decoration: underline;
}

/* Dark Mode */
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1A1A2E;
    --card-bg: #22223A;
    --text: #EDEDEE;
    --text-secondary: #A0A0B0;
    --accent: #E8A88C;
    --accent-light: #CC8A70;
    --accent-subtle: #2A2A42;
    --border: #2E2E44;
    --shadow: 0 2px 12px rgba(0,0,0,0.3);
  }

  pre {
    background: #1E1E32;
    color: #D4D4D8;
  }

  code {
    background: #1E1E32;
  }

  .quiz-options button {
    background: var(--card-bg);
  }

  .quiz-options button:hover {
    background: #2A2A42;
    border-color: var(--accent);
  }

  .quiz-options button.correct {
    background: #0A2E1A;
    border-color: #22c55e;
  }

  .quiz-options button.wrong {
    background: #2E0A0A;
    border-color: #ef4444;
  }

  .quiz-feedback.correct {
    background: #0A2E1A;
    border-color: #22c55e;
  }

  .quiz-feedback.wrong {
    background: #2E0A0A;
    border-color: #ef4444;
  }

  img {
    opacity: 0.85;
  }
}