/* ============================================================
   怪咖产品心理学 · 小红书内容专区样式表 v1.1
   基底：延续 metooshow.com 原站主题（紫蓝渐变 + Bootstrap 5）
   辨识度：小红书品牌红 #ff2442 + 白板板书 + 皮卡丘角标
   说明：本文件为专区独立样式，不修改原站 global.css
   ============================================================ */

:root {
  /* —— 原站主题（保持一致）—— */
  --primary: #667eea;
  --primary-dark: #764ba2;
  --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --accent: #ffc107;
  --light-bg: #f8f9fa;
  --white: #ffffff;
  --text-dark: #333333;
  --text-medium: #666666;
  --text-light: #888888;
  --border: #ececf3;
  --shadow: 0 1px 4px rgba(0, 0, 0, .05);

  /* —— 小红书专区辨识色 —— */
  --xhs-red: #ff2442;
  --xhs-red-dark: #e01835;
  --xhs-red-soft: rgba(255, 36, 66, .08);

  /* —— 白板板书色（粉笔感） —— */
  --board-bg: #fdfcf7;          /* 纸感白板底 */
  --board-line: #e6e1d2;        /* 白板边框 */
  --board-ink: #2b2b2b;         /* 板书墨色 */
  --board-marker-yellow: #fff3b0; /* 粉笔黄 */
  --board-marker-red: #ffd7dd;    /* 粉笔红 */
  --board-marker-blue: #d8ecff;   /* 粉笔蓝 */
  --board-marker-green: #dcf5dc;  /* 粉笔绿 */
  --board-hand: "KaiTi", "STKaiti", "楷体", "PingFang SC", serif;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }

body {
  font-family: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", sans-serif;
  background: var(--light-bg);
  color: var(--text-dark);
  line-height: 1.7;
  padding-top: 56px; /* navbar fixed-top 高度 */
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a { color: var(--primary); text-decoration: none; transition: color .2s ease; }
a:hover { color: var(--primary-dark); }

/* ============================================================
   皮卡丘角标（账号记忆点，每页固定出现）
   使用说明：当前为文字/emoji 占位，后续替换为真实皮卡丘图：
   <span class="pika-badge"><img src="assets/img/pika.png" alt="皮卡丘"></span>
   ============================================================ */
.pika-badge {
  position: absolute;
  top: 12px; right: 14px;
  z-index: 5;
  display: inline-flex; align-items: center; gap: 4px;
  background: #ffd94a;              /* 皮卡丘黄 */
  color: #6b4e00;
  border: 2px solid #fff;
  border-radius: 20px;
  padding: 3px 10px;
  font-size: .68rem; font-weight: 700;
  box-shadow: 0 2px 8px rgba(0,0,0,.18);
  white-space: nowrap;
}
.pika-badge img { width: 22px; height: 22px; border-radius: 50%; object-fit: cover; }

/* ---------- 导航（沿用原站 dark navbar，active 用小红书红） ---------- */
.navbar {
  background-color: rgba(0, 0, 0, .7);
  padding: 10px 0;
  box-shadow: 0 2px 10px rgba(0, 0, 0, .15);
}
.navbar-dark { background-color: #1a1a1a !important; }
.navbar-nav .nav-link {
  color: #fff !important;
  font-weight: 500;
  padding: .3rem .8rem !important;
  font-size: .95rem;
  position: relative;
  transition: all .3s ease;
}
.navbar-nav .nav-link:hover { color: var(--accent) !important; }
.navbar-nav .nav-link::after {
  content: '';
  position: absolute;
  width: 0; height: 2px;
  bottom: 0; left: 0;
  background: var(--accent);
  transition: width .3s ease;
}
.navbar-nav .nav-link:hover::after { width: 100%; }
.navbar-nav .nav-link.xhs-active { color: #ff7d8f !important; }
.navbar-nav .nav-link.xhs-active::after { width: 100%; background: var(--xhs-red); }
@media (max-width: 991px) {
  .navbar-nav { flex-wrap: wrap; white-space: normal; margin-top: 10px; }
  .navbar-nav .nav-item { margin: 5px 0; }
}

/* ============================================================
   总览页 Hero（白板板书背景视觉）
   ============================================================ */
.page-hero {
  position: relative;
  background: var(--primary-gradient);
  color: #fff;
  padding: 84px 20px 56px;
  text-align: center;
  overflow: hidden;
}
.page-hero::before { /* 白板板书感：细线网格背景 */
  content: '';
  position: absolute; inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,.06) 1px, transparent 1px);
  background-size: 28px 28px;
  pointer-events: none;
}
.page-hero h1 { font-size: 2.3rem; font-weight: 700; position: relative; }
.page-hero .sub { max-width: 820px; margin: 18px auto 0; font-size: 1.05rem; opacity: .93; line-height: 1.9; position: relative; }
.page-hero .badge {
  position: relative;
  display: inline-block;
  background: rgba(255, 255, 255, .18);
  padding: 6px 16px; border-radius: 20px;
  font-size: .9rem; margin-bottom: 14px;
}
.hero-cta { position: relative; margin-top: 26px; display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }
.hero-cta .btn-x {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 10px 24px; border-radius: 24px;
  font-size: .92rem; font-weight: 600;
  transition: all .25s ease;
}
.hero-cta .btn-x.primary { background: var(--xhs-red); color: #fff; }
.hero-cta .btn-x.primary:hover { background: var(--xhs-red-dark); transform: translateY(-2px); box-shadow: 0 6px 16px rgba(255,36,66,.35); }
.hero-cta .btn-x.ghost { background: rgba(255,255,255,.16); color: #fff; border: 1px solid rgba(255,255,255,.45); }
.hero-cta .btn-x.ghost:hover { background: rgba(255,255,255,.28); transform: translateY(-2px); }

/* 内容线导航 tab */
.line-tabs {
  max-width: 1080px;
  margin: 26px auto 0;
  padding: 0 20px;
  display: flex; gap: 10px; justify-content: center; flex-wrap: wrap;
}
.line-tab {
  display: inline-block;
  background: #fff; border: 1px solid var(--border);
  color: var(--text-medium);
  padding: 8px 20px; border-radius: 22px;
  font-size: .86rem; font-weight: 600;
  box-shadow: var(--shadow);
  transition: all .25s ease;
}
.line-tab:hover { border-color: var(--primary); color: var(--primary); transform: translateY(-2px); }
.line-tab.active { background: var(--xhs-red); color: #fff; border-color: var(--xhs-red); }

/* ============================================================
   总览页：卡片网格（延续原站 chap-grid 交互语言）
   ============================================================ */
.xhs-grid {
  max-width: 1080px;
  margin: 30px auto 80px;
  padding: 0 20px;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 20px;
}
.xhs-card {
  display: flex; flex-direction: column;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 14px;
  overflow: hidden;
  text-decoration: none; color: inherit;
  transition: all .25s ease;
  box-shadow: var(--shadow);
}
.xhs-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 20px rgba(102, 126, 234, .18);
  border-color: var(--primary);
}

/* 封面占位（白板板书风：期数 + 大字情绪词 + 副题 + 皮卡丘角标文字位） */
.xhs-card-cover {
  position: relative;
  min-height: 158px;
  display: flex; align-items: center; justify-content: center;
  padding: 26px 16px 18px;
  background: var(--board-bg);
  overflow: hidden;
}
.xhs-card-cover::before { /* 板书网格 */
  content: '';
  position: absolute; inset: 0;
  background-image:
    linear-gradient(rgba(0,0,0,.025) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0,0,0,.025) 1px, transparent 1px);
  background-size: 22px 22px;
  pointer-events: none;
}
.xhs-card-cover .cover-badge {
  position: absolute; top: 10px; left: 10px;
  background: var(--xhs-red); color: #fff;
  font-size: .75rem; font-weight: 600;
  padding: 3px 10px; border-radius: 12px;
  z-index: 2;
}
.xhs-card-cover .cover-board {
  position: relative;
  background: #fff;
  border: 1.5px solid var(--board-line);
  border-radius: 8px;
  padding: 14px 18px;
  text-align: center;
  box-shadow: 0 3px 10px rgba(0,0,0,.08);
  max-width: 100%;
}
.cover-emotion {
  font-family: var(--board-hand);
  font-size: 1.18rem; font-weight: 800;
  color: var(--board-ink); line-height: 1.4;
}
.cover-sub {
  margin-top: 6px;
  font-size: .78rem; font-weight: 600;
  color: var(--xhs-red-dark);
  background: var(--xhs-red-soft);
  display: inline-block;
  padding: 2px 12px; border-radius: 12px;
}

/* 卡片正文 */
.xhs-card-body { padding: 16px 18px 18px; display: flex; flex-direction: column; gap: 8px; flex: 1; }
.xhs-card-tags { display: flex; gap: 6px; flex-wrap: wrap; }
.xhs-card-tag {
  font-size: .75rem;
  color: var(--xhs-red-dark);
  background: var(--xhs-red-soft);
  padding: 2px 10px; border-radius: 12px;
}
.xhs-card-tag.course { color: #9a7b00; background: rgba(255,193,7,.18); }
.xhs-card-title { font-weight: 600; color: var(--text-dark); line-height: 1.5; }
.xhs-card-goal { font-size: .86rem; color: #777; line-height: 1.6; flex: 1; }
.xhs-card-quote {
  border-left: 3px solid var(--xhs-red);
  padding-left: 10px;
  font-size: .82rem; color: var(--text-medium);
  font-style: italic;
}

/* 课程入口横幅（总览页底部） */
.course-banner {
  max-width: 1080px; margin: -40px auto 70px; padding: 0 20px;
}
.course-banner .inner {
  background: var(--primary-gradient); color: #fff;
  border-radius: 16px; padding: 30px 28px;
  display: flex; align-items: center; justify-content: space-between;
  gap: 20px; flex-wrap: wrap;
  box-shadow: 0 8px 24px rgba(102,126,234,.3);
}
.course-banner h3 { font-size: 1.2rem; margin-bottom: 6px; }
.course-banner p { font-size: .9rem; opacity: .92; }
.course-banner .btn-x { background: #fff; color: var(--primary-dark); padding: 10px 22px; border-radius: 22px; font-weight: 600; font-size: .9rem; transition: all .25s; }
.course-banner .btn-x:hover { transform: translateY(-2px); box-shadow: 0 6px 14px rgba(0,0,0,.18); }

/* ============================================================
   详情页
   ============================================================ */
.episode-hero {
  position: relative;
  background: var(--primary-gradient);
  color: #fff;
  padding: 60px 20px 46px;
  text-align: center;
  overflow: hidden;
}
.episode-hero::before { /* 板书网格 */
  content: '';
  position: absolute; inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,.05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,.05) 1px, transparent 1px);
  background-size: 26px 26px;
  pointer-events: none;
}
.episode-hero .ep-num {
  position: relative;
  display: inline-block;
  background: var(--xhs-red);
  padding: 4px 14px; border-radius: 16px;
  font-size: .85rem; font-weight: 600;
  margin-bottom: 12px;
}
.episode-hero h1 { font-size: 2.1rem; font-weight: 700; position: relative; padding: 0 10px; }
.episode-hero .ep-sub { max-width: 760px; margin: 14px auto 0; font-size: 1rem; opacity: .93; line-height: 1.8; position: relative; }
.episode-hero .ep-tags { margin-top: 16px; display: flex; gap: 8px; justify-content: center; flex-wrap: wrap; position: relative; }
.episode-hero .ep-tag { background: rgba(255,255,255,.18); padding: 3px 12px; border-radius: 14px; font-size: .8rem; }
.ep-breadcrumb {
  position: relative; margin-top: 18px;
  font-size: .82rem; opacity: .88;
}
.ep-breadcrumb a { color: #fff; border-bottom: 1px dashed rgba(255,255,255,.6); }
.ep-breadcrumb a:hover { color: var(--accent); border-color: var(--accent); }

.episode-body {
  max-width: 920px;
  margin: 36px auto 80px;
  padding: 0 20px;
  display: flex; flex-direction: column; gap: 36px;
}

/* 区块标题 */
.section-head { display: flex; align-items: center; gap: 10px; margin-bottom: 16px; }
.section-head .dot { width: 10px; height: 10px; border-radius: 50%; background: var(--xhs-red); }
.section-head h2 { font-size: 1.35rem; font-weight: 700; color: var(--text-dark); margin: 0; }
.section-head .en { font-size: .75rem; color: var(--text-light); letter-spacing: 1px; text-transform: uppercase; }

/* ============================================================
   板书展示区（白板风格 · 多种布局）
   ============================================================ */
.board-wrap {
  background: var(--board-bg);
  border: 2px solid var(--board-line);
  border-radius: 14px;
  padding: 30px 24px 24px;
  box-shadow: 0 3px 12px rgba(0, 0, 0, .05);
  position: relative;
}
.board-wrap::before {
  content: "🧑‍🏫 板书白板";
  position: absolute; top: -12px; left: 18px;
  background: var(--primary-gradient); color: #fff;
  font-size: .72rem; padding: 3px 12px; border-radius: 10px;
}
.board-head { margin-bottom: 20px; }
.board-title {
  font-size: 1.5rem; font-weight: 800;
  text-align: center; margin-bottom: 4px;
  font-family: var(--board-hand);
}
.board-sub { text-align: center; font-size: .9rem; color: var(--text-medium); }

/* 左右分栏（第1/4期） */
.board-structure { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.board-col {
  background: #fff;
  border: 1px dashed var(--board-line);
  border-radius: 10px;
  padding: 16px;
}
.board-col h4 { font-size: .9rem; margin-bottom: 12px; display: flex; align-items: center; gap: 6px; }
.board-col .badge-x  { background: var(--board-marker-red);  color: #a0303f; padding: 1px 8px; border-radius: 8px; font-size: .75rem; }
.board-col .badge-ok { background: var(--board-marker-blue); color: #1d4e89; padding: 1px 8px; border-radius: 8px; font-size: .75rem; }
.board-item { display: flex; gap: 8px; align-items: flex-start; margin-bottom: 10px; font-size: .9rem; }
.board-item .num {
  flex: 0 0 auto; width: 20px; height: 20px; border-radius: 50%;
  background: var(--board-marker-yellow); border: 1px solid #d8c47a;
  color: #6b5b1f; font-size: .72rem;
  display: flex; align-items: center; justify-content: center;
  font-weight: 600;
}
.board-item .txt { line-height: 1.5; color: var(--board-ink); }
.board-item .x { color: #c0392b; font-weight: 700; }

/* 横向三框（第2期） */
.board-boxes { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.board-box {
  background: #fff;
  border: 1px dashed var(--board-line);
  border-radius: 10px;
  padding: 16px 12px;
  text-align: center;
}
.board-box .box-name {
  display: inline-block;
  background: var(--board-marker-yellow);
  border: 1px solid #e2c94f; color: #6b5b1f;
  font-weight: 800; font-size: 1.02rem;
  padding: 2px 14px; border-radius: 12px;
  font-family: var(--board-hand);
}
.board-box .box-line { margin-top: 10px; font-size: .88rem; color: var(--board-ink); font-weight: 600; }
.board-box .box-example { margin-top: 4px; font-size: .8rem; color: var(--text-medium); }
.board-arrow {
  margin: 16px auto 0; text-align: center;
  font-size: .95rem; color: var(--text-medium);
  font-family: var(--board-hand);
}
.board-arrow b { color: var(--xhs-red-dark); }
.board-arrow .arrow { font-size: 1.2rem; }

/* 纵向尺子式（第3期） */
.board-ruler { display: flex; flex-direction: column; gap: 10px; }
.ruler-row {
  display: grid; grid-template-columns: 58px 1fr 1fr 1fr;
  gap: 12px; align-items: center;
  background: #fff; border: 1px dashed var(--board-line);
  border-radius: 10px; padding: 12px 14px;
}
.ruler-row .r-letter {
  width: 40px; height: 40px; border-radius: 50%;
  background: var(--board-marker-yellow);
  border: 2px solid #e2c94f;
  color: #6b5b1f; font-weight: 800; font-size: 1.1rem;
  display: flex; align-items: center; justify-content: center;
  font-family: var(--board-hand);
}
.ruler-row .r-name { font-weight: 700; font-size: .95rem; color: var(--board-ink); }
.ruler-row .r-scale { font-size: .85rem; color: var(--text-medium); }
.ruler-row .r-scale b { color: var(--xhs-red-dark); }
.ruler-row .r-app {
  font-size: .82rem; color: #1d4e89;
  background: var(--board-marker-blue);
  padding: 4px 10px; border-radius: 8px; text-align: center;
}

/* 左右 + 中间结论（第4期专用） */
.board-conclusion {
  margin: 16px auto 0; text-align: center;
  background: var(--board-marker-green);
  border: 1px dashed #8fca8f; color: #1e6b1e;
  font-weight: 700; font-size: 1rem;
  padding: 12px 18px; border-radius: 10px;
  font-family: var(--board-hand);
}

/* 金字塔（第5期） */
.board-pyramid { display: flex; flex-direction: column; align-items: center; gap: 8px; }
.pyramid-row {
  width: 96%; text-align: center;
  background: #fff; border: 1.5px dashed var(--board-line);
  border-radius: 8px; padding: 12px 10px;
  font-size: .92rem; color: var(--board-ink);
  font-weight: 700;
}
.pyramid-row .py-num { font-size: .72rem; color: var(--xhs-red-dark); display: block; margin-bottom: 2px; }
.pyramid-row.p1 { width: 66%; background: var(--board-marker-yellow); border-color: #e2c94f; }
.pyramid-row.p2 { width: 82%; background: var(--board-marker-blue); border-color: #a9c9ec; }
.pyramid-row.p3 { width: 96%; background: var(--board-marker-green); border-color: #a3d6a3; }

.board-quote {
  margin-top: 20px;
  background: var(--xhs-red-soft);
  border: 1px dashed rgba(255, 36, 66, .35);
  border-radius: 10px;
  padding: 12px 16px;
  text-align: center; font-weight: 700;
  color: var(--xhs-red-dark);
  font-family: var(--board-hand);
  font-size: 1.02rem;
}
.board-note { margin-top: 14px; font-size: .78rem; color: var(--text-light); }
.board-img-placeholder {
  margin-top: 18px;
  border: 2px dashed #d5cfbf; border-radius: 10px;
  padding: 34px 16px; text-align: center;
  color: var(--text-light); font-size: .85rem;
  background: #faf9f2;
}
.board-img-placeholder img { max-width: 100%; border-radius: 8px; box-shadow: var(--shadow); }

/* ============================================================
   关键知识点（术语 → 说人话 → 产品应用）
   ============================================================ */
.knowledge-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 16px; }
.knowledge-card {
  background: #fff; border: 1px solid var(--border);
  border-radius: 12px; padding: 18px 18px 16px;
  box-shadow: var(--shadow);
  display: flex; flex-direction: column; gap: 8px;
}
.knowledge-card .k-term { font-size: 1.02rem; font-weight: 700; color: var(--text-dark); display: flex; align-items: center; gap: 6px; }
.knowledge-card .k-term::before { content: "💡"; font-size: .95rem; }
.knowledge-card .k-human {
  font-size: .85rem; color: var(--text-medium);
  border-left: 3px solid var(--xhs-red); padding-left: 10px;
  line-height: 1.6;
}
.knowledge-card .k-human b { color: var(--text-dark); }
.knowledge-card .k-app {
  margin-top: auto;
  font-size: .8rem; color: #1d4e89;
  background: var(--board-marker-blue);
  border-radius: 8px; padding: 6px 10px; line-height: 1.5;
}
.knowledge-card .k-app b { color: #143a63; }

/* ============================================================
   口播稿区（可折叠）
   ============================================================ */
.script-block {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 10px 24px;
  box-shadow: var(--shadow);
}
.script-part {
  border-bottom: 1px dashed var(--border);
}
.script-part:last-child { border-bottom: none; }
.script-part summary {
  list-style: none;
  cursor: pointer;
  padding: 16px 0 10px;
  display: flex; align-items: center; gap: 8px;
  font-size: 1rem; font-weight: 700; color: var(--text-dark);
}
.script-part summary::-webkit-details-marker { display: none; }
.script-part summary::before { content: "▸"; color: var(--primary); font-size: .9rem; transition: transform .2s; }
.script-part[open] summary::before { transform: rotate(90deg); }
.script-part summary .part-tag {
  background: var(--primary-gradient); color: #fff;
  font-size: .72rem; padding: 2px 10px; border-radius: 10px;
  font-weight: 600; white-space: nowrap;
}
.script-part summary .part-desc { margin-left: auto; font-size: .75rem; color: var(--text-light); font-weight: 400; }
.script-part .part-body { padding: 0 0 16px; }
.script-part p { font-size: .92rem; color: #555; line-height: 1.9; }
.script-quote {
  border-left: 4px solid var(--primary);
  background: #f6f5ff;
  border-radius: 0 8px 8px 0;
  padding: 10px 16px; margin: 6px 0;
  font-size: .92rem; color: #444; line-height: 1.9;
}
.script-quote .who { display: block; font-size: .72rem; color: var(--text-light); margin-bottom: 4px; }

/* ============================================================
   金句区
   ============================================================ */
.quote-section {
  position: relative;
  text-align: center;
  background: var(--primary-gradient);
  border-radius: 14px;
  padding: 36px 24px;
  color: #fff;
  box-shadow: 0 6px 18px rgba(102, 126, 234, .25);
  overflow: hidden;
}
.quote-section::before { /* 板书网格 */
  content: '';
  position: absolute; inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,.05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,.05) 1px, transparent 1px);
  background-size: 24px 24px;
  pointer-events: none;
}
.quote-section .q-label { font-size: .8rem; letter-spacing: 4px; opacity: .85; margin-bottom: 12px; position: relative; }
.quote-section .q-text {
  position: relative;
  font-size: 1.5rem; font-weight: 800; line-height: 1.7;
  font-family: var(--board-hand);
}

/* ============================================================
   标签区 + 下期预告
   ============================================================ */
.meta-section { display: flex; flex-direction: column; gap: 20px; }
.tag-list { display: flex; gap: 8px; flex-wrap: wrap; }
.tag-item {
  background: #fff; border: 1px solid var(--border);
  border-radius: 18px; padding: 5px 14px;
  font-size: .82rem; color: var(--text-medium);
  box-shadow: var(--shadow);
}
.tag-item::before { content: "#"; color: var(--xhs-red); font-weight: 700; }
.next-ep {
  background: var(--board-bg);
  border: 1px dashed var(--board-line);
  border-radius: 12px;
  padding: 16px 20px;
  display: flex; align-items: center; gap: 12px; flex-wrap: wrap;
}
.next-ep .next-label {
  background: var(--xhs-red); color: #fff;
  font-size: .72rem; font-weight: 700;
  padding: 3px 10px; border-radius: 12px;
  white-space: nowrap;
}
.next-ep p { font-size: .92rem; color: var(--text-dark); flex: 1; min-width: 200px; }
.next-ep a { font-weight: 600; font-size: .85rem; white-space: nowrap; }

/* ============================================================
   相关推荐 + 课程入口
   ============================================================ */
.related-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 14px; }
.related-card {
  display: flex; flex-direction: column; gap: 6px;
  background: #fff; border: 1px solid var(--border);
  border-radius: 12px; padding: 14px 16px;
  text-decoration: none; color: inherit;
  transition: all .25s ease; box-shadow: var(--shadow);
}
.related-card:hover { border-color: var(--primary); transform: translateY(-2px); box-shadow: 0 6px 16px rgba(102,126,234,.15); }
.related-card .r-tag { font-size: .72rem; color: var(--xhs-red-dark); background: var(--xhs-red-soft); padding: 2px 8px; border-radius: 10px; align-self: flex-start; }
.related-card .r-title { font-size: .9rem; font-weight: 600; line-height: 1.5; }
.related-card .r-quote { font-size: .78rem; color: var(--text-medium); font-style: italic; }
.course-cta {
  margin-top: 18px;
  background: var(--primary-gradient); color: #fff;
  border-radius: 14px; padding: 22px 24px;
  display: flex; align-items: center; justify-content: space-between;
  gap: 18px; flex-wrap: wrap;
  box-shadow: 0 6px 18px rgba(102,126,234,.25);
}
.course-cta .cta-text { font-size: .95rem; line-height: 1.8; flex: 1; min-width: 220px; }
.course-cta .cta-text b { font-size: 1.05rem; }
.course-cta .btn-x {
  background: #fff; color: var(--primary-dark);
  padding: 10px 22px; border-radius: 22px;
  font-weight: 700; font-size: .88rem; white-space: nowrap;
  transition: all .25s ease;
}
.course-cta .btn-x:hover { transform: translateY(-2px); box-shadow: 0 6px 14px rgba(0,0,0,.18); }

/* ---------- 上下期导航 ---------- */
.episode-nav { display: flex; justify-content: space-between; align-items: center; gap: 12px; flex-wrap: wrap; }
.episode-nav .nav-btn {
  display: inline-flex; align-items: center; gap: 6px;
  background: #fff; border: 1px solid var(--border);
  border-radius: 10px; padding: 10px 16px;
  color: var(--text-dark); font-size: .88rem;
  box-shadow: var(--shadow);
  transition: all .25s ease;
}
.episode-nav .nav-btn:hover { border-color: var(--primary); color: var(--primary); transform: translateY(-2px); }
.episode-nav .nav-btn.back { background: var(--primary-gradient); color: #fff; border: none; }
.episode-nav .nav-btn.back:hover { color: #fff; box-shadow: 0 6px 16px rgba(102, 126, 234, .3); }

/* ---------- 页脚 ---------- */
.site-footer {
  background: #1a1a1a; color: #aaa;
  text-align: center; padding: 24px 20px;
  font-size: .82rem; line-height: 2;
}
.site-footer a { color: #ccc; }
.site-footer a:hover { color: var(--accent); }

/* ---------- 响应式 ---------- */
@media (max-width: 640px) {
  .board-structure { grid-template-columns: 1fr; }
  .board-boxes { grid-template-columns: 1fr; }
  .ruler-row { grid-template-columns: 46px 1fr 1fr; }
  .ruler-row .r-app { grid-column: 1 / -1; text-align: left; }
  .page-hero h1 { font-size: 1.7rem; }
  .episode-hero h1 { font-size: 1.55rem; }
  .board-title { font-size: 1.2rem; }
}

/* ---------- 板书真实图片（白板质感） ---------- */
.board-image {
  width: 100%;
  max-width: 840px;
  margin: 0 auto;
  display: block;
  border-radius: 12px;
  border: 1px solid rgba(0,0,0,.08);
  box-shadow: 0 6px 20px rgba(0,0,0,.14);
}

/* ---------- 总览页卡片封面图 ---------- */
.xhs-card-cover { padding: 0; overflow: hidden; }
.cover-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}
.xhs-card-cover .cover-badge { z-index: 2; }