/* ============================================================
   古筝小课堂 · 古风版 样式表
   陶土暖沙 · 墨绿丝弦 · 东方雅致
   ============================================================ */

/* ===== 设计令牌 ===== */
:root {
  /* 主色：宣纸 + 朱砂 + 靛青 */
  --bg: #F8F2E8;              /* 宣纸底色 */
  --bg-warm: #E8DFD0;          /* 深宣纸 */
  --bg-card: #FDFAF3;          /* 卡片底 */
  --white: #FFFEFA;
  --ink: #2C2C2C;             /* 墨黑 */
  --ink-light: #5A5A5A;        /* 淡墨 */
  --ink-muted: #8A8A8A;        /* 灰墨 */

  --cinnabar: #A0522D;        /* 朱砂红 */
  --cinnabar-light: #C67B5C;
  --cinnabar-dark: #7A3B1F;
  --indigo: #5A7A5E;          /* 靛青 */
  --indigo-light: #7B9E7E;
  --indigo-dark: #3D5A42;
  --bamboo: #7B9E5E;          /* 竹绿 */
  --gold: #8B7355;            /* 古铜金 */
  --sand: #D4C4A8;            /* 砂色 */

  /* 字体 */
  --font-serif: 'Noto Serif SC', 'Songti SC', 'STSong', 'SimSun', serif;
  --font-sans: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;

  /* 字号 */
  --fs-hero: clamp(2rem, 5vw, 3.5rem);
  --fs-h1: clamp(1.5rem, 3.5vw, 2.5rem);
  --fs-h2: clamp(1.25rem, 2.5vw, 1.75rem);
  --fs-h3: 1.15rem;
  --fs-body: 1rem;
  --fs-small: 0.875rem;
  --fs-tiny: 0.75rem;

  /* 间距 */
  --sp-xs: 0.5rem;
  --sp-sm: 0.75rem;
  --sp-md: 1.25rem;
  --sp-lg: 2rem;
  --sp-xl: 3.5rem;
  --sp-2xl: 5rem;

  /* 圆角 */
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-full: 999px;

  /* 阴影 */
  --shadow-soft: 0 2px 12px rgba(92, 74, 40, 0.08);
  --shadow-clay: 0 4px 20px rgba(92, 74, 40, 0.12);
  --shadow-hover: 0 8px 32px rgba(192, 64, 48, 0.15);

  /* 导航高度 */
  --nav-height: 64px;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ===== 基础重置 ===== */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: var(--fs-body);
  line-height: 1.8;
  color: var(--ink);
  background: var(--bg);
  /* 宣纸纹理 */
  background-image:
    radial-gradient(ellipse at top, rgba(184, 146, 60, 0.04), transparent 50%),
    radial-gradient(ellipse at bottom, rgba(192, 64, 48, 0.03), transparent 50%);
  overflow-x: hidden;
}
img { max-width: 100%; height: auto; display: block; }
a { color: var(--cinnabar); text-decoration: none; }

/* ===== 顶部导航 ===== */
.top-nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--nav-height);
  background: rgba(245, 239, 224, 0.88);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid rgba(184, 146, 60, 0.15);
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0 var(--sp-lg);
}
.nav-inner {
  width: 100%;
  max-width: 1200px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--ink);
}
.nav-brand,
.brand {
.brand-text { font-size: 1.25rem; font-weight: 700; font-family: var(--font-serif); color: var(--cinnabar-dark); }
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--cinnabar-dark);
}
.brand-icon {
  width: 36px; height: 36px;
  border-radius: 50%;
  background: var(--cinnabar);
  color: var(--white);
  display: flex; align-items: center; justify-content: center;
  font-family: var(--font-serif);
  font-size: 1.2rem;
  box-shadow: 0 2px 8px rgba(192, 64, 48, 0.3);
}
.nav-links {
  list-style: none;
  display: flex;
  gap: 0.25rem;
  margin: 0; padding: 0;
}
.nav-links a {
  display: block;
  padding: 8px 16px;
  border-radius: var(--radius-full);
  font-size: var(--fs-small);
  color: var(--ink-light);
  transition: var(--transition);
  cursor: pointer;
  font-family: var(--font-serif);
}
.nav-links a:hover {
  background: rgba(192, 64, 48, 0.08);
  color: var(--cinnabar-dark);
}
.nav-links a.active {
  background: var(--cinnabar);
  color: var(--white);
  box-shadow: 0 2px 8px rgba(192, 64, 48, 0.25);
}
.nav-actions {
  display: flex;
  align-items: center;
  gap: var(--sp-sm);
}
.nav-actions { display: flex; gap: 6px; }
.btn-print {
  padding: 6px 14px;
  border: 1px solid var(--cinnabar);
  background: transparent;
  color: var(--cinnabar);
  border-radius: var(--radius-full);
  font-size: var(--fs-tiny);
  cursor: pointer;
  transition: var(--transition);
  font-family: var(--font-sans);
}
.btn-print:hover {
  background: var(--cinnabar);
  color: var(--white);
}
.btn-print.child-btn {
  border-color: var(--indigo);
  color: var(--indigo);
}
.btn-print.child-btn:hover {
  background: var(--indigo);
  color: var(--white);
}
.nav-toggle {
  display: none;
  background: none; border: none;
  font-size: 1.5rem;
  color: var(--ink);
  cursor: pointer;
}

/* 移动端菜单 */
.nav-menu-mobile {
  display: none;
  position: fixed;
  top: var(--nav-height); left: 0; right: 0;
  background: rgba(245, 239, 224, 0.95);
  backdrop-filter: blur(20px);
  flex-direction: column;
  padding: var(--sp-sm) var(--sp-lg);
  z-index: 999;
  border-bottom: 1px solid rgba(184, 146, 60, 0.15);
}
.nav-menu-mobile.open { display: flex; }
.nav-menu-mobile a {
  padding: 12px 0;
  color: var(--ink);
  font-family: var(--font-serif);
  border-bottom: 1px solid rgba(184, 146, 60, 0.1);
}
.nav-menu-mobile a.active { color: var(--cinnabar); font-weight: 700; }

/* ===== 移动端导航浮窗 ===== */
.nav-fab {
  display: none;
  position: fixed;
  bottom: 20px; left: 20px;
  width: 52px; height: 52px;
  border-radius: 50%;
  background: rgba(192, 64, 48, 0.92);
  backdrop-filter: blur(10px);
  color: var(--white);
  border: none;
  cursor: pointer;
  z-index: 1001;
  box-shadow: 0 4px 16px rgba(192, 64, 48, 0.35);
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2px;
  transition: var(--transition);
}
.nav-fab:hover { transform: scale(1.08); }
.nav-fab-icon { font-size: 1.1rem; }
.nav-fab-label {
  font-size: 0.625rem;
  font-family: var(--font-serif);
}
.nav-fab-mask {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.25);
  backdrop-filter: blur(2px);
  z-index: 1001;
}
.nav-fab-mask.show { display: block; }
.nav-fab-panel {
  position: fixed;
  top: 0; left: 0; bottom: 0;
  width: 220px;
  background: rgba(245, 239, 224, 0.96);
  backdrop-filter: blur(20px);
  border-right: 1px solid rgba(184, 146, 60, 0.2);
  transform: translateX(-100%);
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  z-index: 1002;
  padding: 80px 16px 20px;
  display: flex;
  flex-direction: column;
  gap: 4px;
  overflow-y: auto;
}
.nav-fab-panel.open { transform: translateX(0); }
.nav-fab-title {
  font-family: var(--font-serif);
  font-size: var(--fs-small);
  color: var(--ink-muted);
  margin-bottom: var(--sp-sm);
  padding-bottom: 8px;
  border-bottom: 1px solid rgba(184, 146, 60, 0.15);
}
.nav-fab-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 14px;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: var(--transition);
  min-height: 48px;
  font-size: var(--fs-small);
  color: var(--ink);
  font-family: var(--font-serif);
}
.nav-fab-item:hover { background: rgba(192, 64, 48, 0.08); }
.nav-fab-item.active {
  background: var(--cinnabar);
  color: var(--white);
}
.nav-fab-num {
  width: 24px; height: 24px;
  border-radius: 50%;
  background: var(--cinnabar);
  color: var(--white);
  display: flex; align-items: center; justify-content: center;
  font-size: 0.75rem;
  flex-shrink: 0;
}
.nav-fab-item.active .nav-fab-num {
  background: var(--white);
  color: var(--cinnabar);
}
.nav-fab-print {
  margin-top: auto;
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding-top: 16px;
  border-top: 1px solid rgba(184, 146, 60, 0.15);
}

/* ===== Hero ===== */
.hero {
  padding: calc(var(--nav-height) + 40px) var(--sp-lg) var(--sp-2xl);
  max-width: 1080px;
  margin: 0 auto;
}
.hero-inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--sp-xl);
  align-items: center;
}
.hero-text h1 {
  font-family: var(--font-serif);
  font-size: var(--fs-hero);
  font-weight: 900;
  line-height: 1.2;
  color: var(--cinnabar-dark);
  margin-bottom: var(--sp-sm);
}
.hero-text .hero-sub {
  font-size: 1.1rem;
  color: var(--ink-light);
  line-height: 1.8;
  margin-bottom: var(--sp-md);
  max-width: 45ch;
}
.hero-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: var(--sp-md);
}
.hero-tag {
  padding: 4px 14px;
  border-radius: var(--radius-full);
  background: rgba(43, 77, 126, 0.08);
  color: var(--indigo);
  font-size: var(--fs-tiny);
  font-weight: 600;
}
.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-sm);
  margin-top: var(--sp-md);
}
.hero-img,
  width: 100%;
  aspect-ratio: 16/9;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-clay);
  background: var(--bg-warm);
  border: 1px solid rgba(184, 146, 60, 0.2);
}
.hero-img img {
  width: 100%; height: 100%;
  object-fit: contain;
}

/* ===== 主内容区 ===== */
.main-content {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 var(--sp-lg);
}
.section-anchor {
  scroll-margin-top: calc(var(--nav-height) + 20px);
}
.chapter-head {
  margin: 0 auto var(--sp-lg);
  max-width: 800px;
  padding-top: var(--sp-xl);
  text-align: center;
}
.section-badge {
  display: inline-block;
  padding: 4px 16px;
  border-radius: var(--radius-full);
  background: linear-gradient(135deg, var(--cinnabar), var(--cinnabar-light));
  color: var(--white);
  font-size: var(--fs-tiny);
  font-weight: 700;
  margin-bottom: var(--sp-sm);
  font-family: var(--font-serif);
}
.chapter-head h2 {
  font-family: var(--font-serif);
  font-size: var(--fs-h1);
  color: var(--cinnabar-dark);
  margin-bottom: var(--sp-sm);
}
.chapter-head .section-subtitle {
  font-size: var(--fs-h3);
  color: var(--ink-muted);
  font-weight: 400;
}

.content-block {
  margin: 0 auto var(--sp-lg);
  max-width: 800px;
}
.content-block h3 {
  font-family: var(--font-serif);
  font-size: var(--fs-h2);
  color: var(--indigo);
  margin-bottom: var(--sp-sm);
  margin-top: var(--sp-lg);
  border-left: 3px solid var(--cinnabar);
  padding-left: 12px;
}
.content-block p {
  font-size: var(--fs-body);
  color: var(--ink);
  margin-bottom: var(--sp-sm);
  max-width: 65ch;
  line-height: 1.8;
}
.content-block ul, .content-block ol {
  margin-left: 20px;
  margin-bottom: var(--sp-sm);
}
.content-block li {
  margin-bottom: 6px;
  line-height: 1.7;
}
.content-block strong {
  color: var(--cinnabar-dark);
  font-weight: 700;
}

/* ===== 卡片网格 ===== */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--sp-lg);
  margin: 0 auto var(--sp-xl);
  max-width: 1000px;
}

.img-card {
  background: var(--bg-card);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-clay);
  transition: all var(--transition);
  display: flex;
  flex-direction: column;
  cursor: pointer;
  border: 1px solid rgba(184, 146, 60, 0.15);
}
.img-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}
.img-card .img-wrapper {
  width: 100%;
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background: linear-gradient(180deg, var(--bg) 0%, var(--bg-warm) 100%);
}
.img-card .img-wrapper img {
  width: 100%; height: 100%;
  object-fit: contain;
  transition: transform 0.4s ease;
}
.img-card:hover .img-wrapper img {
  transform: scale(1.05);
}
.img-card .img-caption {
  padding: var(--sp-md);
  flex: 1;
}
.img-card .img-caption h4 {
  font-family: var(--font-serif);
  font-size: var(--fs-h3);
  color: var(--cinnabar-dark);
  margin-bottom: var(--sp-xs);
}
.img-card .img-caption p {
  font-size: var(--fs-small);
  color: var(--ink-light);
  line-height: 1.6;
}

/* ===== 提示框 ===== */
.tip, .callout, .warn-box {
  max-width: 800px;
  margin: var(--sp-md) auto;
  padding: var(--sp-md);
  border-radius: var(--radius-md);
  border-left: 4px solid;
}
.tip {
  background: rgba(43, 77, 126, 0.06);
  border-color: var(--indigo);
}
.tip-title, .callout-title, .warn-title {
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: var(--fs-h3);
  margin-bottom: var(--sp-sm);
}
.tip-title { color: var(--indigo); }
.callout {
  background: rgba(192, 64, 48, 0.05);
  border-color: var(--cinnabar);
}
.callout-title { color: var(--cinnabar-dark); }
.warn-box {
  background: rgba(184, 146, 60, 0.08);
  border-color: var(--gold);
}
.warn-title { color: var(--gold); }
.tip p, .callout p, .warn-box p {
  margin-bottom: var(--sp-xs);
  font-size: var(--fs-body);
  line-height: 1.7;
}

/* ===== 故事卡片 ===== */
.story-card {
  max-width: 800px;
  margin: 0 auto var(--sp-lg);
  padding: var(--sp-md);
  border-radius: var(--radius-md);
  background: var(--bg-card);
  border: 1px solid rgba(184, 146, 60, 0.2);
  box-shadow: var(--shadow-soft);
}
.story-card h4 {
  font-family: var(--font-serif);
  font-size: var(--fs-h3);
  color: var(--cinnabar-dark);
  margin-bottom: var(--sp-sm);
  display: flex;
  align-items: center;
  gap: 8px;
}
.story-card .story-meta {
  font-size: var(--fs-tiny);
  color: var(--ink-muted);
  margin-bottom: var(--sp-sm);
}
.story-card p {
  font-size: var(--fs-body);
  line-height: 1.8;
  margin-bottom: var(--sp-sm);
  color: var(--ink);
}

/* ===== 参考来源 ===== */
.sources-section {
  max-width: 800px;
  margin: var(--sp-xl) auto;
  padding: var(--sp-md);
  border-top: 2px solid rgba(184, 146, 60, 0.3);
  border-bottom: 2px solid rgba(184, 146, 60, 0.3);
}
.sources-section h3 {
  font-family: var(--font-serif);
  color: var(--cinnabar-dark);
  font-size: var(--fs-h2);
}
.sources-section ol {
  padding-left: 20px;
  font-size: var(--fs-small);
  color: var(--ink-light);
  line-height: 1.8;
}
.verification-date {
  font-size: var(--fs-tiny);
  color: var(--ink-muted);
  margin-top: var(--sp-sm);
}

/* ===== 滚动渐入 ===== */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ===== 响应式 ===== */
@media (max-width: 768px) {
  .nav-links { display: none; }
  .nav-actions { display: none; }
  .nav-toggle { display: block; }
  .nav-fab { display: flex !important; }

  .hero {
    padding: calc(var(--nav-height) + 20px) var(--sp-sm) var(--sp-xl);
  }
  .hero-inner {
    grid-template-columns: 1fr;
    gap: var(--sp-lg);
  }
  .hero-text h1 { font-size: 2rem; }
  .hero-text .hero-sub { font-size: 0.95rem; }

  .chapter-head { padding-top: var(--sp-lg); }
  .card-grid { grid-template-columns: 1fr; }

  .content-block p { max-width: 100%; }
}

@media (min-width: 769px) {
  .nav-toggle { display: none; }
  .nav-menu-mobile { display: none !important; }
}

/* ===== 打印样式 ===== */
@media print {
  body { background: white; color: black; }
  .top-nav, .nav-fab, .nav-fab-mask, .nav-fab-panel,
  .nav-menu-mobile, .hero-actions, .nav-actions { display: none !important; }
  .hero { padding: 0; }
  .reveal { opacity: 1 !important; transform: none !important; }
  .img-card, .content-block, .chapter-head {
    page-break-inside: avoid;
    break-inside: avoid;
  }
  h2, h3, h4 { break-after: avoid; }
}

body.print-adult .reveal { opacity: 1 !important; transform: none !important; }
body.print-adult .img-card,
body.print-adult .content-block,
body.print-adult .chapter-head { display: block !important; }

body.print-child .content-block { display: none; }
body.print-child .img-card { break-inside: avoid; page-break-inside: avoid; }
body.print-child .img-card .img-caption p { font-size: 0.8rem; }
body.print-child .img-card .img-caption h4 { font-size: 1.1rem; }
body.print-child .reveal { opacity: 1 !important; transform: none !important; }
body.print-child .story-card { display: none; }
body.print-child .tip, body.print-child .callout, body.print-child .warn-box { display: none; }

@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  * { animation: none !important; transition: none !important; }
}

/* ===== Shared Components (supplement) ===== */
.btn-primary { display: inline-block; background: var(--cinnabar); color: var(--white); padding: 10px 24px; border-radius: var(--radius-full); text-decoration: none; font-weight: 700; transition: var(--transition); border: none; font-size: var(--fs-body); cursor: pointer; box-shadow: 0 4px 16px rgba(192,64,48,0.25); }
.btn-primary:hover { opacity: 0.9; transform: translateY(-1px); }
.btn-ghost { background: transparent; border: 1px solid var(--cinnabar); color: var(--cinnabar); padding: 8px 18px; border-radius: var(--radius-full); cursor: pointer; font-size: var(--fs-small); transition: var(--transition); }
.btn-ghost:hover { background: var(--cinnabar); color: var(--white); }
.hero-badge { display: inline-block; background: rgba(192,64,48,0.1); color: var(--cinnabar-dark); font-size: var(--fs-tiny); padding: 4px 12px; border-radius: var(--radius-full); margin-bottom: var(--sp-sm); }
.chapter { max-width: 1200px; margin: 0 auto; padding: var(--sp-xl) var(--sp-lg); }
.chapter-no { font-size: 3rem; font-weight: 900; color: var(--cinnabar); font-family: var(--font-serif); line-height: 1; opacity: 0.8; }
.chapter-head p { color: var(--ink-light); margin: 0; font-size: var(--fs-small); }
.chapter-footer { display: flex; justify-content: space-between; gap: var(--sp-md); margin-top: var(--sp-xl); padding-top: var(--sp-lg); border-top: 1px solid rgba(0,0,0,0.06); }
.page-nav { text-decoration: none; color: var(--ink); padding: var(--sp-sm) var(--sp-md); border: 1px solid rgba(0,0,0,0.08); border-radius: var(--radius-md); transition: var(--transition); }
.page-nav:hover { background: rgba(0,0,0,0.02); border-color: var(--cinnabar); }
.page-nav span { display: block; font-size: var(--fs-tiny); color: var(--ink-light); }
.page-nav.disabled { opacity: 0.4; pointer-events: none; }
.callout { background: rgba(0,0,0,0.02); border-left: 3px solid var(--cinnabar); border-radius: var(--radius-sm); padding: var(--sp-md) var(--sp-lg); margin: var(--sp-lg) auto; max-width: 800px; }
.callout h3 { font-family: var(--font-serif); color: var(--cinnabar-dark); margin-bottom: var(--sp-sm); }
.callout p { margin: 0.4rem 0; }
.qa-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: var(--sp-sm); margin-top: var(--sp-md); }
.qa-grid details { background: rgba(255,255,255,0.5); border-radius: var(--radius-sm); padding: var(--sp-sm) var(--sp-md); border: 1px solid rgba(0,0,0,0.05); }
.qa-grid summary { cursor: pointer; font-weight: 700; color: var(--ink); }
.qa-grid p { margin: 0.5rem 0 0; }
.sources-box ul { margin: var(--sp-sm) 0; padding-left: 1.2rem; }
.sources-box li { margin: 0.3rem 0; }
.verify-date { font-size: var(--fs-tiny); color: var(--ink-light); margin-top: var(--sp-sm); }
.site-footer { text-align: center; padding: var(--sp-lg); color: var(--ink-light); font-size: var(--fs-small); border-top: 1px solid rgba(0,0,0,0.06); }
.adult-only { }