/* =========================================
   演说家培训 - 前端样式
   Aesthetic: Aurora Dawn（极光黎明）
   浅色科幻 · 充满希望与成长感
   Colors: #F0F4FF / #3B6EFF / #8B5CF6 / #F59E0B
   Fonts: Orbitron + DM Sans
   ========================================= */

/* --- CSS Variables --- */
:root {
  /* Core palette — 浅色背景体系 */
  --space-black:   #F0F4FF;   /* 原深黑 → 极光白底 */
  --deep-navy:     #E8EEFF;   /* 原深海蓝 → 淡蓝白 */
  --dark-panel:    #FFFFFF;   /* 原暗面板 → 纯白面板 */
  --panel:         #F5F7FF;   /* 原面板 → 微蓝白面板 */
  --panel-light:   #EEF2FF;   /* 原浅面板 → 淡紫白 */

  /* Accent colors — 星云蓝·极光紫·日出金 */
  --cyan:          #3B6EFF;   /* 星云蓝（替代青蓝） */
  --cyan-dim:      #2B5AE8;
  --cyan-glow:     rgba(59, 110, 255, 0.25);
  --cyan-subtle:   rgba(59, 110, 255, 0.07);
  --purple:        #8B5CF6;   /* 极光紫 */
  --purple-dim:    #7C3AED;
  --purple-glow:   rgba(139, 92, 246, 0.25);
  --orange:        #F59E0B;   /* 日出金 */
  --orange-dim:    #D97706;
  --orange-glow:   rgba(245, 158, 11, 0.3);

  /* Text — 深色文字在浅背景上 */
  --text-primary:  #1A1F3C;   /* 深宇蓝黑，主文字 */
  --text-secondary: #4A5580;  /* 星雾灰蓝，次文字 */
  --text-muted:    #8A96C0;   /* 淡雾色，辅助文字 */
  --text-ghost:    rgba(74, 85, 128, 0.35);

  /* Borders / Dividers */
  --border-glow:   rgba(59, 110, 255, 0.18);
  --border-dim:    rgba(74, 85, 128, 0.14);
  --border-bright: rgba(59, 110, 255, 0.45);

  /* Legacy aliases for compatibility */
  --black:         var(--space-black);
  --red:           var(--orange);
  --red-dark:      var(--orange-dim);
  --cream:         var(--dark-panel);
  --white:         var(--deep-navy);
  --gray:          var(--text-secondary);
  --gray-light:    var(--text-muted);
  --gray-xlight:   var(--border-dim);

  /* Typography */
  --font-display: 'Orbitron', 'DM Sans', 'PingFang SC', sans-serif;
  --font-body:    'DM Sans', 'PingFang SC', sans-serif;

  /* Shadows — 浅色系阴影更轻柔 */
  --shadow-sm:  0 2px 12px rgba(59, 110, 255, 0.08);
  --shadow-md:  0 8px 32px rgba(59, 110, 255, 0.12), 0 2px 8px rgba(0,0,0,0.06);
  --shadow-lg:  0 20px 60px rgba(59, 110, 255, 0.16), 0 4px 16px rgba(0,0,0,0.08);
  --shadow-cyan: 0 4px 24px rgba(59, 110, 255, 0.35), 0 0 48px rgba(59, 110, 255, 0.12);
  --shadow-purple: 0 4px 24px rgba(139, 92, 246, 0.35), 0 0 48px rgba(139, 92, 246, 0.12);
  --shadow-orange: 0 4px 20px rgba(245, 158, 11, 0.3);

  /* Misc */
  --radius:    6px;
  --radius-lg: 12px;
  --trans:     all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ─────────────────────────────────────────
   GOOGLE FONTS IMPORT (Orbitron)
───────────────────────────────────────── */
@import url('https://fonts.googleapis.com/css2?family=Orbitron:wght@400;500;700;900&family=DM+Sans:wght@300;400;500;600&display=swap');

/* --- Reset & Base --- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: var(--font-body);
  background-color: var(--space-black);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
  background-image:
    radial-gradient(ellipse at 10% 0%, rgba(59,110,255,0.07) 0%, transparent 50%),
    radial-gradient(ellipse at 90% 100%, rgba(139,92,246,0.06) 0%, transparent 50%),
    radial-gradient(ellipse at 50% 50%, rgba(245,158,11,0.03) 0%, transparent 60%);
}
img, video { max-width: 100%; display: block; }
a { text-decoration: none; color: inherit; }
button { cursor: pointer; border: none; background: none; font-family: inherit; }
ul { list-style: none; }
input, select { font-family: inherit; }

/* --- Utility --- */
.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 40px;
}
@media (max-width: 768px) {
  .container { padding: 0 20px; }
}

/* Cyber grid line decoration */
.cyber-grid-bg::after {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(0,212,255,0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0,212,255,0.03) 1px, transparent 1px);
  background-size: 60px 60px;
  pointer-events: none;
}

/* =========================================
   HEADER
   ========================================= */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  background: rgba(240, 244, 255, 0.88);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-glow);
  transition: var(--trans);
}
.site-header::before {
  content: '';
  position: absolute;
  bottom: 0; left: 0; right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--cyan), var(--purple), transparent);
  opacity: 0.4;
}
.header-inner {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 40px;
  height: 70px;
  display: flex;
  align-items: center;
  gap: 48px;
}
.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}
.logo-mark {
  width: 36px; height: 36px;
  /*background: linear-gradient(135deg, var(--cyan), var(--purple));*/
  color: var(--space-black);
  font-family: var(--font-display);
  font-weight: 900;
  font-size: 18px;
  display: flex; align-items: center; justify-content: center;
  border-radius: 6px;
  /*box-shadow: var(--shadow-cyan);*/
}
.logo-text {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 15px;
  color: var(--text-primary);
  letter-spacing: 1px;
  text-transform: uppercase;
}
.logo-text em {
  font-style: normal;
  color: var(--text-secondary);
  font-weight: 400;
  font-size: 11px;
  display: block;
  line-height: 1;
  letter-spacing: 2px;
}
.main-nav {
  display: flex;
  align-items: center;
  gap: 32px;
  margin-left: auto;
}
.nav-link {
  font-size: 13px;
  font-weight: 500;
  color: var(--text-secondary);
  position: relative;
  padding-bottom: 2px;
  transition: var(--trans);
  letter-spacing: 0.5px;
}
.nav-link::after {
  content: '';
  position: absolute;
  bottom: -2px; left: 0;
  width: 0; height: 1px;
  background: linear-gradient(90deg, var(--cyan), var(--purple));
  transition: var(--trans);
}
.nav-link:hover, .nav-link.active {
  color: var(--text-primary);
}
.nav-link:hover::after, .nav-link.active::after {
  width: 100%;
}
.header-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}
.btn-search {
  width: 36px; height: 36px;
  display: flex; align-items: center; justify-content: center;
  color: var(--text-secondary);
  border-radius: 8px;
  border: 1px solid var(--border-glow);
  transition: var(--trans);
}
.btn-search:hover {
  background: var(--cyan-subtle);
  color: var(--cyan);
  border-color: var(--border-bright);
}
.btn-admin {
  padding: 8px 18px;
  background: transparent;
  border: 1px solid var(--border-bright);
  color: var(--cyan);
  font-size: 13px;
  font-weight: 500;
  border-radius: var(--radius);
  display: flex; align-items: center; gap: 6px;
  transition: var(--trans);
  letter-spacing: 0.3px;
}
.btn-admin:hover {
  background: var(--cyan-subtle);
  box-shadow: var(--shadow-cyan);
}
.mobile-menu-btn {
  display: none;
  font-size: 20px;
  color: var(--text-primary);
}

/* =========================================
   HERO — 全屏视频背景版
   ========================================= */
.hero {
  min-height: 100vh;
  padding-top: 70px;
  position: relative;
  display: flex;
  align-items: center;
  overflow: hidden;
}

/* ── 视频背景层 ── */
.hero-video-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
}
.hero-video-el {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center;
  /* 视频未加载时的占位背景 */
  background: linear-gradient(160deg, #1A1F3C 0%, #0D1240 50%, #1C0F3F 100%);
}
/* 渐变遮罩：左侧暗+可读，右侧半透明露出视频 */
.hero-video-overlay {
  position: absolute;
  inset: 0;
  background:
    linear-gradient(
      to right,
      rgba(10, 14, 40, 0.82) 0%,
      rgba(10, 14, 40, 0.65) 45%,
      rgba(10, 14, 40, 0.35) 70%,
      rgba(10, 14, 40, 0.20) 100%
    );
}
/* 科幻网格叠层 */
.hero-video-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(59,110,255,0.07) 1px, transparent 1px),
    linear-gradient(90deg, rgba(59,110,255,0.07) 1px, transparent 1px);
  background-size: 80px 80px;
  pointer-events: none;
}

/* ── 内容布局 ── */
.hero-content {
  position: relative;
  z-index: 1;
  max-width: 1280px;
  margin: 0 auto;
  padding: 80px 40px;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 80px;
  align-items: center;
  width: 100%;
}
.hero-tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 3px;
  text-transform: uppercase;
  color: #7DD3FA;
  border: 1px solid rgba(125, 211, 250, 0.4);
  padding: 5px 12px;
  border-radius: 2px;
  margin-bottom: 28px;
  background: rgba(59, 110, 255, 0.15);
  backdrop-filter: blur(4px);
}
.hero-tag::before {
  content: '';
  width: 6px; height: 6px;
  border-radius: 50%;
  background: #7DD3FA;
  box-shadow: 0 0 8px #7DD3FA;
}
.hero-title {
  font-family: var(--font-display);
  font-size: clamp(44px, 5vw, 76px);
  font-weight: 900;
  line-height: 1.1;
  color: #FFFFFF;
  margin-bottom: 24px;
  letter-spacing: -0.5px;
  text-shadow: 0 2px 20px rgba(0,0,0,0.3);
}
.title-accent {
  color: #7DD3FA;
  position: relative;
  display: inline-block;
  text-shadow: 0 0 40px rgba(125,211,250,0.6), 0 2px 20px rgba(0,0,0,0.3);
}
.title-accent::after {
  content: '';
  position: absolute;
  bottom: 2px; left: 0; right: 0;
  height: 3px;
  background: linear-gradient(90deg, #7DD3FA, var(--purple));
  opacity: 0.7;
  border-radius: 2px;
}
.hero-desc {
  font-size: 15px;
  color: rgba(220, 230, 255, 0.85);
  line-height: 1.8;
  margin-bottom: 40px;
  max-width: 420px;
  text-shadow: 0 1px 8px rgba(0,0,0,0.4);
}
.hero-cta {
  display: flex;
  align-items: center;
  gap: 20px;
  margin-bottom: 48px;
  flex-wrap: wrap;
}
.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 30px;
  background: linear-gradient(135deg, var(--cyan), var(--purple));
  color: var(--space-black);
  font-size: 14px;
  font-weight: 700;
  border-radius: var(--radius);
  transition: var(--trans);
  box-shadow: var(--shadow-cyan);
  letter-spacing: 0.5px;
}
.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(0,212,255,0.5), 0 0 60px rgba(123,47,255,0.3);
  filter: brightness(1.1);
}
.btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 26px;
  border: 1px solid rgba(255, 255, 255, 0.55);
  color: #FFFFFF;
  font-size: 14px;
  font-weight: 600;
  border-radius: var(--radius);
  transition: var(--trans);
  background: rgba(255, 255, 255, 0.08);
  backdrop-filter: blur(8px);
  text-shadow: 0 1px 6px rgba(0,0,0,0.3);
}
.btn-secondary:hover {
  background: rgba(125, 211, 250, 0.18);
  border-color: #7DD3FA;
  color: #7DD3FA;
  box-shadow: 0 4px 20px rgba(125,211,250,0.25);
}
.hero-stats {
  display: flex;
  align-items: center;
  gap: 32px;
}
.stat-item { text-align: left; }
.stat-num {
  display: block;
  font-family: var(--font-display);
  font-size: 34px;
  font-weight: 700;
  color: var(--cyan);
  line-height: 1;
  margin-bottom: 4px;
  text-shadow: 0 0 20px rgba(0,212,255,0.5);
}
.stat-label {
  font-size: 11px;
  color: var(--text-muted);
  letter-spacing: 1px;
  text-transform: uppercase;
}
.stat-divider {
  width: 1px;
  height: 40px;
  background: var(--border-glow);
}

/* =========================================
   HERO SEARCH
   ========================================= */
.hero-search {
  margin-top: 36px;
}
.hero-search-box {
  display: flex;
  align-items: center;
  background: rgba(10, 14, 40, 0.65);
  border: 1px solid rgba(125,211,250,0.35);
  border-radius: 50px;
  padding: 6px 6px 6px 22px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.3), 0 0 0 1px rgba(125,211,250,0.05);
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
  gap: 12px;
  max-width: 520px;
  backdrop-filter: blur(16px);
}
.hero-search-box:focus-within {
  border-color: #7DD3FA;
  box-shadow: 0 4px 24px rgba(125,211,250,0.3), 0 4px 20px rgba(0,0,0,0.3);
}
.hero-search-icon {
  color: rgba(200,220,255,0.6);
  font-size: 14px;
  flex-shrink: 0;
  transition: color 0.2s;
}
.hero-search-box:focus-within .hero-search-icon {
  color: #7DD3FA;
}
.hero-search-input {
  flex: 1;
  border: none;
  outline: none;
  background: transparent;
  font-size: 14px;
  color: #FFFFFF;
  font-weight: 400;
  min-width: 0;
  padding: 8px 0;
}
.hero-search-input::placeholder {
  color: rgba(200,220,255,0.45);
  font-weight: 300;
}
.hero-search-btn {
  flex-shrink: 0;
  padding: 9px 22px;
  background: linear-gradient(135deg, #3B6EFF, #8B5CF6);
  color: #FFFFFF;
  font-size: 13px;
  font-weight: 700;
  border-radius: 50px;
  letter-spacing: 0.5px;
  transition: all 0.2s ease;
  cursor: pointer;
  white-space: nowrap;
}
.hero-search-btn:hover {
  filter: brightness(1.15);
  box-shadow: 0 4px 20px rgba(59,110,255,0.5);
}
.hero-search-tags {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-top: 14px;
  flex-wrap: wrap;
}
.search-hint {
  font-size: 11px;
  color: rgba(200,220,255,0.55);
  letter-spacing: 0.5px;
}
.search-tag {
  font-size: 11px;
  color: rgba(200,220,255,0.75);
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(255,255,255,0.15);
  border-radius: 50px;
  padding: 4px 12px;
  cursor: pointer;
  transition: var(--trans);
  font-family: var(--font-body);
  backdrop-filter: blur(4px);
}
.search-tag:hover {
  background: rgba(125,211,250,0.15);
  color: #7DD3FA;
  border-color: rgba(125,211,250,0.4);
}

/* ── Hero Stats ── */
.hero-stats {
  display: flex;
  align-items: center;
  gap: 32px;
  margin-top: 48px;
}
.stat-item { text-align: left; }
.stat-num {
  display: block;
  font-family: var(--font-display);
  font-size: 34px;
  font-weight: 700;
  color: #7DD3FA;
  line-height: 1;
  margin-bottom: 4px;
  text-shadow: 0 0 20px rgba(125,211,250,0.6);
}
.stat-label {
  font-size: 11px;
  color: rgba(200,220,255,0.6);
  letter-spacing: 1px;
  text-transform: uppercase;
}
.stat-divider {
  width: 1px;
  height: 40px;
  background: rgba(255,255,255,0.15);
}

/* ── Hero Right：科技风学员视频库 ── */
.hero-right {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
}
.featured-card {
  background: var(--dark-panel);
  border: 1px solid var(--border-glow);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  cursor: pointer;
  transition: var(--trans);
}
.featured-card:hover {
  transform: translateY(-6px);
  border-color: var(--border-bright);
  box-shadow: var(--shadow-lg), var(--shadow-cyan);
}
.featured-card-thumb {
  position: relative;
  aspect-ratio: 16/9;
  overflow: hidden;
}
.featured-card-thumb img {
  width: 100%; height: 100%;
  object-fit: cover;
  opacity: 0.7;
  transition: var(--trans);
  filter: hue-rotate(10deg) saturate(1.2);
}
.featured-card:hover .featured-card-thumb img { opacity: 0.85; transform: scale(1.04); }
.featured-play-btn {
  position: absolute;
  inset: 0;
  display: flex; align-items: center; justify-content: center;
}
.play-circle {
  width: 72px; height: 72px;
  background: rgba(0,212,255,0.15);
  backdrop-filter: blur(8px);
  border: 2px solid rgba(0,212,255,0.5);
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  color: var(--cyan);
  font-size: 22px;
  transition: var(--trans);
  box-shadow: 0 0 20px rgba(0,212,255,0.3);
}
.featured-card:hover .play-circle {
  background: rgba(0,212,255,0.3);
  border-color: var(--cyan);
  transform: scale(1.08);
  box-shadow: var(--shadow-cyan);
}
.featured-card-info {
  padding: 20px 24px;
}
.featured-cat-badge {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 2px;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 1px;
  text-transform: uppercase;
  margin-bottom: 10px;
  border: 1px solid var(--border-glow);
}
.featured-card-title {
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 8px;
  line-height: 1.3;
  letter-spacing: 0.3px;
}
.featured-card-meta {
  font-size: 12px;
  color: var(--text-muted);
  display: flex; align-items: center; gap: 16px;
}
.featured-card-meta i { font-size: 10px; }

/* =========================================
   HERO VIDEO LIBRARY BADGE — 右侧科技徽标
   ========================================= */
.hero-vl-badge {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 36px;
  padding: 56px 52px 50px;
  /* 毛玻璃深色面板 */
  background: rgba(8, 12, 35, 0.5);
  backdrop-filter: blur(20px);
  border: 1px solid rgba(125, 211, 250, 0.2);
  border-radius: 20px;
  box-shadow:
    0 0 80px rgba(59, 110, 255, 0.18),
    0 0 160px rgba(139, 92, 246, 0.10),
    inset 0 1px 0 rgba(255,255,255,0.08);
  min-width: 420px;
  max-width: 500px;
  overflow: hidden;
}

/* 顶部装饰线 */
.vl-deco-top {
  display: flex;
  align-items: center;
  gap: 8px;
  width: 100%;
}
.vl-deco-line {
  flex: 1;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(125,211,250,0.6), transparent);
}
.vl-deco-dot {
  width: 5px; height: 5px;
  border-radius: 50%;
  background: rgba(125,211,250,0.7);
  box-shadow: 0 0 6px rgba(125,211,250,0.8);
}

/* 主标题区 */
.vl-title-wrap {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}
.vl-label-en {
  font-family: var(--font-display);
  font-size: 13px;
  font-weight: 500;
  letter-spacing: 8px;
  color: rgba(125, 211, 250, 0.6);
  text-transform: uppercase;
}
.vl-label-en--btm {
  letter-spacing: 5px;
  font-size: 11px;
  color: rgba(139,92,246,0.7);
}

/* 汉字竖排大字 */
.vl-title-main {
  display: flex;
  align-items: center;
  gap: 10px;
}
.vl-char {
  font-family: var(--font-display);
  font-size: clamp(52px, 5.5vw, 72px);
  font-weight: 900;
  color: #FFFFFF;
  /* 每个字加微弱蓝光 */
  text-shadow:
    0 0 24px rgba(125,211,250,0.5),
    0 0 70px rgba(59,110,255,0.25),
    0 2px 6px rgba(0,0,0,0.4);
  letter-spacing: 0;
  line-height: 1;
  transition: transform 0.2s ease, text-shadow 0.2s ease;
  display: inline-block;
}
.vl-char:hover {
  transform: translateY(-5px) scale(1.10);
  text-shadow:
    0 0 36px rgba(125,211,250,0.9),
    0 0 90px rgba(59,110,255,0.5);
}

/* 数据指标 */
.vl-metrics {
  display: flex;
  align-items: center;
  gap: 32px;
  padding: 22px 32px;
  background: rgba(59,110,255,0.08);
  border: 1px solid rgba(125,211,250,0.15);
  border-radius: 10px;
  width: 100%;
  justify-content: center;
}
.vl-metric {
  display: flex;
  align-items: baseline;
  gap: 4px;
  flex-direction: row;
  flex-wrap: wrap;
  justify-content: center;
  text-align: center;
  flex-direction: column;
  align-items: center;
}
.vl-metric-num {
  font-family: var(--font-display);
  font-size: 38px;
  font-weight: 700;
  color: #7DD3FA;
  line-height: 1;
  text-shadow: 0 0 20px rgba(125,211,250,0.6);
}
.vl-metric-unit {
  font-family: var(--font-display);
  font-size: 16px;
  font-weight: 600;
  color: rgba(125,211,250,0.7);
}
.vl-metric-desc {
  font-size: 12px;
  color: rgba(200,220,255,0.5);
  letter-spacing: 1px;
  margin-top: 6px;
}
.vl-metric-sep {
  width: 1px;
  height: 52px;
  background: rgba(125,211,250,0.2);
}

/* 扫描线动画 */
.vl-scan {
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 2px;
  background: linear-gradient(90deg,
    transparent 0%,
    rgba(125,211,250,0.0) 20%,
    rgba(125,211,250,0.9) 50%,
    rgba(125,211,250,0.0) 80%,
    transparent 100%
  );
  animation: vl-scan-move 3s linear infinite;
  pointer-events: none;
}
@keyframes vl-scan-move {
  0%   { top: 0;    opacity: 0; }
  5%   { opacity: 1; }
  95%  { opacity: 1; }
  100% { top: 100%; opacity: 0; }
}

/* 四角装饰 */
.vl-corners { pointer-events: none; }
.vl-corner {
  position: absolute;
  width: 20px; height: 20px;
  border-color: rgba(125,211,250,0.6);
  border-style: solid;
}
.vl-corner--tl { top: 14px; left: 14px;  border-width: 2px 0 0 2px; }
.vl-corner--tr { top: 14px; right: 14px; border-width: 2px 2px 0 0; }
.vl-corner--bl { bottom: 14px; left: 14px;  border-width: 0 0 2px 2px; }
.vl-corner--br { bottom: 14px; right: 14px; border-width: 0 2px 2px 0; }

/* Hero scroll hint */
.hero-scroll-hint {
  position: absolute;
  bottom: 40px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  color: rgba(255, 255, 255, 0.85);
  font-size: 14px;
  font-weight: 500;
  letter-spacing: 3px;
  text-transform: uppercase;
  text-shadow: 0 0 12px rgba(125, 211, 250, 0.7), 0 1px 6px rgba(0,0,0,0.4);
  animation: bounce 2s infinite;
  z-index: 1;
  cursor: default;
}
.hero-scroll-hint i {
  font-size: 18px;
  color: #7DD3FA;
  text-shadow: 0 0 14px rgba(125, 211, 250, 0.9);
}
@keyframes bounce {
  0%, 100% { transform: translateX(-50%) translateY(0); }
  50% { transform: translateX(-50%) translateY(8px); }
}

/* =========================================
   SECTIONS COMMON
   ========================================= */
.section-latest,
.section-categories,
.section-hot {
  padding: 100px 0;
}

/* =========================================
   SECTION HEADER V2 — 新版章节标题
   ========================================= */
.section-header-v2 {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  margin-bottom: 44px;
  gap: 16px;
}
.shv2-eyebrow {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-display);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 4px;
  text-transform: uppercase;
  color: var(--cyan);
  margin-bottom: 10px;
}
.shv2-dot {
  display: inline-block;
  width: 6px; height: 6px;
  border-radius: 50%;
  background: var(--cyan);
  box-shadow: 0 0 8px var(--cyan);
  animation: dotPulse 2s ease-in-out infinite;
}
.shv2-dot--purple { background: var(--purple); box-shadow: 0 0 8px var(--purple); }
.shv2-dot--orange { background: var(--orange); box-shadow: 0 0 8px var(--orange); }
@keyframes dotPulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(0.7); }
}
.shv2-title {
  font-family: var(--font-display);
  font-size: clamp(26px, 3.2vw, 40px);
  font-weight: 800;
  color: var(--text-primary);
  line-height: 1.15;
  letter-spacing: -0.5px;
}
.shv2-more {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-secondary);
  padding: 8px 18px;
  border: 1px solid var(--border-dim);
  border-radius: 40px;
  text-decoration: none;
  transition: var(--trans);
  white-space: nowrap;
  margin-bottom: 2px;
}
.shv2-more:hover {
  color: var(--cyan);
  border-color: var(--cyan);
  background: var(--cyan-subtle);
  transform: translateX(3px);
}

/* =========================================
   LATEST VIDEOS — 横向滚动轨道
   ========================================= */
.latest-track-wrap {
  position: relative;
  overflow: hidden;
}
.latest-track {
  display: flex;
  gap: 22px;
  overflow-x: auto;
  scroll-behavior: smooth;
  scrollbar-width: none;
  padding-bottom: 6px;
  /* 左右渐出 */
  -webkit-mask-image: linear-gradient(to right, transparent 0%, black 4%, black 92%, transparent 100%);
  mask-image: linear-gradient(to right, transparent 0%, black 4%, black 92%, transparent 100%);
}
.latest-track::-webkit-scrollbar { display: none; }
.latest-track .video-card {
  flex: 0 0 300px;
  width: 300px;
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1), box-shadow 0.3s;
}
.latest-track .video-card:hover {
  transform: translateY(-6px) scale(1.02);
  box-shadow: var(--shadow-lg);
  z-index: 2;
}
.latest-track .video-card-thumb {
  aspect-ratio: 16/9;
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
}
/* 轨道翻页按钮 */
.track-nav {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 42px; height: 42px;
  border-radius: 50%;
  background: var(--dark-panel);
  border: 1px solid var(--border-glow);
  color: var(--text-primary);
  font-size: 14px;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  transition: var(--trans);
  box-shadow: var(--shadow-md);
  z-index: 10;
}
.track-nav:hover {
  background: var(--cyan);
  color: #fff;
  border-color: var(--cyan);
  box-shadow: var(--shadow-cyan);
}
.track-prev { left: 0; }
.track-next { right: 0; }

/* =========================================
   CATEGORIES — 全宽横幅卡片
   ========================================= */
.section-categories {
  background:
    linear-gradient(180deg, var(--panel-light) 0%, var(--space-black) 100%);
  border-top: 1px solid var(--border-glow);
  border-bottom: 1px solid var(--border-glow);
  position: relative;
  overflow: hidden;
}
.section-categories::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(59,110,255,0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(59,110,255,0.03) 1px, transparent 1px);
  background-size: 80px 80px;
  pointer-events: none;
}
.cat-banner-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 16px;
  position: relative; z-index: 1;
}
.cat-banner {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0;
  padding: 36px 24px 28px;
  border-radius: 16px;
  border: 1px solid var(--border-dim);
  overflow: hidden;
  text-decoration: none;
  cursor: pointer;
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1), box-shadow 0.3s, border-color 0.3s;
}
.cat-banner:hover {
  transform: translateY(-8px);
  box-shadow: 0 24px 60px rgba(0,0,0,0.12);
}
/* 背景渐变 */
.cat-banner--beginner  { background: linear-gradient(160deg, #EEF4FF 0%, #F4F0FF 100%); border-color: rgba(59,110,255,0.15); }
.cat-banner--advanced  { background: linear-gradient(160deg, #FFFBEF 0%, #FFF4DC 100%); border-color: rgba(245,158,11,0.18); }
.cat-banner--pro       { background: linear-gradient(160deg, #F5F0FF 0%, #FFF0F8 100%); border-color: rgba(139,92,246,0.18); }
.cat-banner--business  { background: linear-gradient(160deg, #EDFFF8 0%, #F0FAFF 100%); border-color: rgba(16,185,129,0.18); }
.cat-banner--corporate { background: linear-gradient(160deg, #FFF0F8 0%, #FFF5EE 100%); border-color: rgba(236,72,153,0.18); }
/* 悬停发光 */
.cat-banner--beginner:hover  { border-color: rgba(59,110,255,0.45);  box-shadow: 0 20px 50px rgba(59,110,255,0.15); }
.cat-banner--advanced:hover  { border-color: rgba(245,158,11,0.45);  box-shadow: 0 20px 50px rgba(245,158,11,0.15); }
.cat-banner--pro:hover       { border-color: rgba(139,92,246,0.45);  box-shadow: 0 20px 50px rgba(139,92,246,0.15); }
.cat-banner--business:hover  { border-color: rgba(16,185,129,0.45);  box-shadow: 0 20px 50px rgba(16,185,129,0.15); }
.cat-banner--corporate:hover { border-color: rgba(236,72,153,0.45);  box-shadow: 0 20px 50px rgba(236,72,153,0.15); }
/* 角装饰光晕 */
.cb-glow {
  position: absolute;
  width: 120px; height: 120px;
  border-radius: 50%;
  top: -30px; right: -30px;
  pointer-events: none;
  opacity: 0.22;
  transition: opacity 0.3s;
}
.cat-banner--beginner  .cb-glow { background: radial-gradient(circle, #3B6EFF, transparent 70%); }
.cat-banner--advanced  .cb-glow { background: radial-gradient(circle, #F59E0B, transparent 70%); }
.cat-banner--pro       .cb-glow { background: radial-gradient(circle, #8B5CF6, transparent 70%); }
.cat-banner--business  .cb-glow { background: radial-gradient(circle, #10B981, transparent 70%); }
.cat-banner--corporate .cb-glow { background: radial-gradient(circle, #EC4899, transparent 70%); }
.cat-banner:hover .cb-glow { opacity: 0.40; }
/* 图标 */
.cb-icon {
  width: 52px; height: 52px;
  border-radius: 14px;
  display: flex; align-items: center; justify-content: center;
  font-size: 22px;
  margin-bottom: 20px;
  transition: transform 0.3s;
}
.cat-banner--beginner  .cb-icon { background: rgba(59,110,255,0.12);  color: #2B5AE8; }
.cat-banner--advanced  .cb-icon { background: rgba(245,158,11,0.14);  color: #B97200; }
.cat-banner--pro       .cb-icon { background: rgba(139,92,246,0.14);  color: #7C3AED; }
.cat-banner--business  .cb-icon { background: rgba(16,185,129,0.12);  color: #059669; }
.cat-banner--corporate .cb-icon { background: rgba(236,72,153,0.12);  color: #BE185D; }
.cat-banner:hover .cb-icon { transform: scale(1.12) rotate(-4deg); }
/* 正文 */
.cb-body { flex: 1; }
.cb-num {
  font-family: var(--font-display);
  font-size: 32px;
  font-weight: 900;
  line-height: 1;
  margin-bottom: 8px;
  letter-spacing: -1px;
}
.cat-banner--beginner  .cb-num { color: #2B5AE8; }
.cat-banner--advanced  .cb-num { color: #B97200; }
.cat-banner--pro       .cb-num { color: #7C3AED; }
.cat-banner--business  .cb-num { color: #059669; }
.cat-banner--corporate .cb-num { color: #BE185D; }
.cb-name {
  font-family: var(--font-display);
  font-size: 13px;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: 0.3px;
  margin-bottom: 5px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.cb-desc {
  font-size: 11px;
  color: var(--text-muted);
  line-height: 1.5;
}
/* 箭头 */
.cb-arrow {
  position: absolute;
  bottom: 20px; right: 20px;
  width: 28px; height: 28px;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 11px;
  border: 1px solid transparent;
  transition: var(--trans);
  opacity: 0;
  transform: translateX(-4px);
}
.cat-banner--beginner  .cb-arrow { border-color: rgba(59,110,255,0.4);  color: #2B5AE8; }
.cat-banner--advanced  .cb-arrow { border-color: rgba(245,158,11,0.4);  color: #B97200; }
.cat-banner--pro       .cb-arrow { border-color: rgba(139,92,246,0.4);  color: #7C3AED; }
.cat-banner--business  .cb-arrow { border-color: rgba(16,185,129,0.4);  color: #059669; }
.cat-banner--corporate .cb-arrow { border-color: rgba(236,72,153,0.4);  color: #BE185D; }
.cat-banner:hover .cb-arrow { opacity: 1; transform: translateX(0); }

/* =========================================
   HOT VIDEOS — 聚光灯布局
   ========================================= */
.section-latest { background: var(--space-black); }
.section-hot { background: linear-gradient(180deg, var(--panel-light) 0%, var(--space-black) 100%); }
.spotlight-layout {
  display: grid;
  grid-template-columns: 1.55fr 1fr;
  gap: 24px;
  align-items: start;
}
/* 主卡 */
.spotlight-main .video-card {
  height: 100%;
  border-radius: 16px;
  border: 1px solid var(--border-glow);
  box-shadow: var(--shadow-md);
  transition: transform 0.4s cubic-bezier(0.34, 1.56, 0.64, 1), box-shadow 0.4s, border-color 0.4s;
}
.spotlight-main .video-card:hover {
  transform: translateY(-8px) scale(1.02);
  box-shadow: 0 32px 64px rgba(0, 212, 255, 0.2), 0 16px 32px rgba(0, 0, 0, 0.3);
  border-color: var(--cyan);
  z-index: 10;
}
.spotlight-main .video-card-thumb {
  aspect-ratio: 16/10;
}
.spotlight-main .video-card-title {
  font-size: 18px;
  line-height: 1.35;
  -webkit-line-clamp: 3;
  margin-bottom: 10px;
}
/* 主卡排名徽标 */
.spotlight-main .video-card {
  position: relative;
}
.spotlight-rank {
  position: absolute;
  top: -1px; left: 16px;
  z-index: 10;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: 12px;
  letter-spacing: 1.5px;
  padding: 6px 18px;
  background: linear-gradient(135deg, var(--orange) 0%, #F97316 50%, #EA580C 100%);
  color: #fff;
  border-radius: 0 0 12px 12px;
  box-shadow: 0 4px 12px rgba(249, 115, 22, 0.4), 0 2px 4px rgba(0, 0, 0, 0.1);
  backdrop-filter: blur(8px);
  border: 1px solid rgba(255, 255, 255, 0.2);
  text-transform: uppercase;
  transition: transform 0.3s cubic-bezier(0.34, 1.56, 0.64, 1), box-shadow 0.3s;
}
.spotlight-main .video-card:hover .spotlight-rank {
  transform: scale(1.1);
  box-shadow: 0 8px 20px rgba(249, 115, 22, 0.5), 0 4px 8px rgba(0, 0, 0, 0.2);
}
.spotlight-rank i {
  color: #FFEDD5;
  animation: firePulse 2s ease-in-out infinite;
}
@keyframes firePulse {
  0%, 100% { transform: scale(1) rotate(-5deg); opacity: 1; }
  50% { transform: scale(1.15) rotate(5deg); opacity: 0.9; }
}
/* 副卡列 */
.spotlight-side {
  display: flex;
  flex-direction: column;
  gap: 8px;
  align-items: stretch;
}
.spotlight-side .video-card {
  display: flex;
  flex-direction: row;
  border-radius: 12px;
  min-height: 95px;
  border: 1px solid var(--border-dim);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
}
.spotlight-side .video-card:hover {
  border-color: var(--border-glow);
  box-shadow: var(--shadow-md), 0 0 20px rgba(0, 212, 255, 0.15);
  transform: translateX(6px) scale(1.02);
}
.spotlight-side .video-card-thumb {
  width: 130px;
  min-width: 130px;
  flex-shrink: 0;
  aspect-ratio: 4/3;
}
.spotlight-side .video-card-thumb img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.spotlight-side .video-card-overlay {
  display: none;
}
.spotlight-side .video-card-info {
  padding: 11px 14px;
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
  flex: 1;
  min-width: 0;
  overflow: hidden;
}
.spotlight-side .video-card-title {
  font-size: 13px;
  -webkit-line-clamp: 2;
  margin-bottom: 4px;
  flex-shrink: 0;
}
.spotlight-side .video-card-tags { display: none; }
/* 副卡排名序号 */
.side-rank-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-display);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.5px;
  color: var(--text-muted);
  margin-bottom: 4px;
  flex-shrink: 0;
  padding: 2px 6px;
  background: linear-gradient(135deg, #FEF3C7 0%, #FDE68A 100%);
  border-radius: 4px;
  border: 1px solid #FBBF24;
  box-shadow: 0 2px 4px rgba(251, 191, 36, 0.2);
  transition: transform 0.3s cubic-bezier(0.34, 1.56, 0.64, 1), box-shadow 0.3s;
}
.spotlight-side .video-card:hover .side-rank-badge {
  transform: scale(1.05);
  box-shadow: 0 4px 8px rgba(251, 191, 36, 0.3);
}
.side-rank-num {
  font-size: 18px;
  font-weight: 900;
  background: linear-gradient(135deg, #F59E0B 0%, #D97706 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1;
  letter-spacing: -0.5px;
}
.side-rank-badge span:last-child {
  color: #92400E;
  text-transform: uppercase;
}
.section-header {
  display: flex;
  align-items: flex-end;
  gap: 20px;
  margin-bottom: 48px;
  flex-wrap: wrap;
}
.section-label {
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 4px;
  text-transform: uppercase;
  color: var(--cyan);
  padding-bottom: 4px;
  border-bottom: 1px solid var(--cyan);
  margin-right: 4px;
  font-family: var(--font-display);
}
.section-title {
  font-family: var(--font-display);
  font-size: clamp(24px, 3vw, 36px);
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.2;
  letter-spacing: 0.5px;
}
.section-more {
  margin-left: auto;
  font-size: 13px;
  font-weight: 500;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 6px;
  transition: var(--trans);
}
.section-more:hover { color: var(--cyan); }

/* =========================================
   VIDEO CARD
   ========================================= */
.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 24px;
}
.video-grid-full {
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
}
.video-card {
  background: var(--dark-panel);
  border: 1px solid var(--border-dim);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: var(--trans);
  cursor: pointer;
  position: relative;
  overflow: visible;
}

/* 波纹效果 */
.ripple {
  position: absolute;
  border-radius: 50%;
  transform: scale(0);
  animation: rippleAnim 0.6s ease-out;
  pointer-events: none;
  background: radial-gradient(circle, rgba(0, 212, 255, 0.4) 0%, rgba(0, 212, 255, 0.1) 60%, transparent 100%);
}

@keyframes rippleAnim {
  to {
    transform: scale(2.5);
    opacity: 0;
  }
}
.video-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--border-glow);
}
.video-card-thumb {
  position: relative;
  aspect-ratio: 16/9;
  overflow: hidden;
  background: var(--panel);
}
.video-card-thumb img {
  width: 100%; height: 100%;
  object-fit: cover;
  transition: var(--trans);
}
.video-card:hover .video-card-thumb img { transform: scale(1.05); }
.thumb-placeholder {
  width: 100%; height: 100%;
  display: flex; align-items: center; justify-content: center;
  background: linear-gradient(135deg, var(--panel) 0%, var(--dark-panel) 100%);
}
.thumb-placeholder i { font-size: 36px; color: var(--text-muted); }
.video-card-overlay {
  position: absolute;
  inset: 0;
  background: rgba(5, 11, 24, 0);
  display: flex; align-items: center; justify-content: center;
  transition: var(--trans);
}
.video-card:hover .video-card-overlay {
  background: rgba(5, 11, 24, 0.5);
}
.overlay-play {
  width: 56px; height: 56px;
  background: rgba(0,212,255,0.2);
  border: 2px solid var(--cyan);
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  color: var(--cyan);
  font-size: 18px;
  opacity: 0;
  transform: scale(0.8);
  transition: var(--trans);
  box-shadow: var(--shadow-cyan);
}
.video-card:hover .overlay-play {
  opacity: 1;
  transform: scale(1);
}
.video-card-badge {
  position: absolute;
  top: 12px; left: 12px;
  padding: 4px 10px;
  border-radius: 3px;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.5px;
  backdrop-filter: blur(6px);
}
.badge-beginner  { background: rgba(59,110,255,0.10);  color: #2B5AE8; border: 1px solid rgba(59,110,255,0.3); }
.badge-advanced  { background: rgba(245,158,11,0.12);  color: #B97200; border: 1px solid rgba(245,158,11,0.35); }
.badge-pro       { background: rgba(139,92,246,0.12);  color: #7C3AED; border: 1px solid rgba(139,92,246,0.35); }
.badge-business  { background: rgba(16,185,129,0.10);  color: #059669; border: 1px solid rgba(16,185,129,0.3); }
.badge-corporate { background: rgba(236,72,153,0.10);  color: #BE185D; border: 1px solid rgba(236,72,153,0.3); }

.video-card-duration {
  position: absolute;
  bottom: 10px; right: 12px;
  background: rgba(5,11,24,0.85);
  color: #ffffff;
  font-size: 10px;
  font-weight: 600;
  padding: 3px 7px;
  border-radius: 3px;
  border: 1px solid var(--border-dim);
  letter-spacing: 0.3px;
}
.video-card-info {
  padding: 16px 18px 18px;
}
.video-card-title {
  font-family: var(--font-display);
  font-size: 14px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 6px;
  line-height: 1.4;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  letter-spacing: 0.3px;
}
.video-card-student {
  font-size: 12px;
  color: var(--text-secondary);
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 6px;
}
.video-card-student i { font-size: 10px; color: var(--cyan); }
.video-card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  margin-bottom: 10px;
}
.vc-tag {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 10px;
  padding: 2px 8px;
  border-radius: 20px;
  font-weight: 500;
  max-width: 120px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  border: 1px solid;
}
.vc-tag i { font-size: 9px; flex-shrink: 0; }
.vc-tag-company  { background: rgba(59,110,255,0.08);   color: #2B5AE8; border-color: rgba(59,110,255,0.22); }
.vc-tag-city     { background: rgba(16,185,129,0.08);   color: #047857; border-color: rgba(16,185,129,0.22); }
.vc-tag-industry { background: rgba(245,158,11,0.08);   color: #92640c; border-color: rgba(245,158,11,0.22); }
.modal-extra-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin: 8px 0 12px;
}
.modal-extra-tags .vc-tag {
  font-size: 11px;
  padding: 3px 10px;
  max-width: none;
}
.video-card-meta {
  display: flex;
  align-items: center;
  gap: 16px;
  font-size: 11px;
  color: var(--text-muted);
  border-top: 1px solid var(--border-dim);
  padding-top: 10px;
  margin-top: 4px;
}
.video-card-meta span { display: flex; align-items: center; gap: 4px; }
.video-card-meta i { font-size: 9px; color: var(--text-muted); }
.video-card-download {
  margin-left: auto;
  color: var(--text-secondary);
  padding: 4px 8px;
  border-radius: var(--radius);
  transition: var(--trans);
  display: flex; align-items: center; gap: 4px;
  font-size: 11px;
  border: 1px solid transparent;
}
.video-card-download:hover {
  background: var(--cyan-subtle);
  color: var(--cyan);
  border-color: var(--border-bright);
}

/* =========================================
   CATEGORIES GRID
   ========================================= */
.section-categories {
  background: var(--panel-light);
  border-top: 1px solid var(--border-glow);
  border-bottom: 1px solid var(--border-glow);
  position: relative;
}
.section-categories::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(59,110,255,0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(59,110,255,0.035) 1px, transparent 1px);
  background-size: 60px 60px;
  pointer-events: none;
}

/* ── 第一行：3列等宽 ── */
.cat-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  position: relative;
  z-index: 1;
}

/* ── 第二行：2张卡居中，与第一行列宽对齐 ── */
.cat-grid-row2 {
  display: flex;
  justify-content: center;
  gap: 20px;
  margin-top: 20px;
  position: relative;
  z-index: 1;
}
/* 每张卡宽度 = 1/3 总宽 - gap，与上方3列网格完全对齐 */
.cat-grid-row2 .cat-card {
  flex: 0 0 calc(33.333% - 14px);
  max-width: calc(33.333% - 14px);
}
/* 两张卡占第2、3列，视觉上居中 */
.cat-grid-row2 .cat-card:first-child { grid-column: 2; }
.cat-grid-row2 .cat-card:last-child  { grid-column: 3; }

/* ── 公共卡片样式 ── */
.cat-card {
  background: var(--dark-panel);
  border: 1px solid var(--border-dim);
  border-radius: var(--radius-lg);
  padding: 32px 28px 28px;
  display: flex;
  flex-direction: row;
  align-items: center;
  gap: 20px;
  position: relative;
  overflow: hidden;
  transition: var(--trans);
  text-decoration: none;
}
.cat-card:hover {
  transform: translateY(-5px);
  border-color: var(--border-bright);
  box-shadow: var(--shadow-md);
}

/* 顶部彩条 */
.cat-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 3px;
  transition: opacity 0.25s;
}
.cat-beginner::before  { background: linear-gradient(90deg, var(--cyan),    var(--purple)); }
.cat-advanced::before  { background: linear-gradient(90deg, var(--orange),  #F97316); }
.cat-pro::before       { background: linear-gradient(90deg, var(--purple),  #EC4899); }
.cat-business::before  { background: linear-gradient(90deg, #10B981,        var(--cyan)); }
.cat-corporate::before { background: linear-gradient(90deg, #EC4899,        var(--purple)); }

/* 悬停时微发光底层 */
.cat-beginner:hover  { box-shadow: var(--shadow-md), 0 0 30px rgba(59,110,255,0.12); }
.cat-advanced:hover  { box-shadow: var(--shadow-md), 0 0 30px rgba(245,158,11,0.12); }
.cat-pro:hover       { box-shadow: var(--shadow-md), 0 0 30px rgba(139,92,246,0.14); }
.cat-business:hover  { box-shadow: var(--shadow-md), 0 0 30px rgba(16,185,129,0.12); }
.cat-corporate:hover { box-shadow: var(--shadow-md), 0 0 30px rgba(236,72,153,0.12); }

/* 图标区 */
.cat-icon {
  width: 56px; height: 56px;
  border-radius: 14px;
  display: flex; align-items: center; justify-content: center;
  font-size: 22px;
  flex-shrink: 0;
  transition: var(--trans);
}
.cat-beginner  .cat-icon { background: rgba(59,110,255,0.10);  color: #2B5AE8;  border: 1px solid rgba(59,110,255,0.25); }
.cat-advanced  .cat-icon { background: rgba(245,158,11,0.12);  color: #B97200;  border: 1px solid rgba(245,158,11,0.3); }
.cat-pro       .cat-icon { background: rgba(139,92,246,0.12);  color: #7C3AED;  border: 1px solid rgba(139,92,246,0.3); }
.cat-business  .cat-icon { background: rgba(16,185,129,0.10);  color: #059669;  border: 1px solid rgba(16,185,129,0.25); }
.cat-corporate .cat-icon { background: rgba(236,72,153,0.10);  color: #BE185D;  border: 1px solid rgba(236,72,153,0.25); }

.cat-card:hover .cat-icon { transform: scale(1.1); }

/* 文字区 */
.cat-info {
  flex: 1;
  min-width: 0;
}
.cat-info h3 {
  font-family: var(--font-display);
  font-size: 14px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 5px;
  letter-spacing: 0.5px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.cat-info p {
  font-size: 12px;
  color: var(--text-secondary);
  line-height: 1.5;
}
.cat-count {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 11px;
  font-weight: 600;
  color: var(--text-muted);
  margin-top: 8px;
  letter-spacing: 0.5px;
}
.cat-count::before {
  content: '';
  display: inline-block;
  width: 5px; height: 5px;
  border-radius: 50%;
  background: currentColor;
  opacity: 0.6;
}

/* 箭头 */
.cat-arrow {
  flex-shrink: 0;
  width: 32px; height: 32px;
  border-radius: 8px;
  background: var(--panel);
  border: 1px solid var(--border-dim);
  display: flex; align-items: center; justify-content: center;
  color: var(--text-muted);
  font-size: 12px;
  transition: var(--trans);
}
.cat-beginner:hover  .cat-arrow { background: rgba(59,110,255,0.12);  border-color: rgba(59,110,255,0.4);  color: #2B5AE8; }
.cat-advanced:hover  .cat-arrow { background: rgba(245,158,11,0.12);  border-color: rgba(245,158,11,0.4);  color: #B97200; }
.cat-pro:hover       .cat-arrow { background: rgba(139,92,246,0.12);  border-color: rgba(139,92,246,0.4);  color: #7C3AED; }
.cat-business:hover  .cat-arrow { background: rgba(16,185,129,0.12);  border-color: rgba(16,185,129,0.4);  color: #059669; }
.cat-corporate:hover .cat-arrow { background: rgba(236,72,153,0.12);  border-color: rgba(236,72,153,0.4);  color: #BE185D; }
.cat-card:hover .cat-arrow { transform: translateX(3px); }

/* =========================================
   HOT VIDEOS LAYOUT
   ========================================= */
.hot-layout {
  display: grid;
  grid-template-columns: 1.4fr 1fr;
  grid-template-rows: auto auto;
  gap: 24px;
}
.hot-card-big {
  grid-row: span 2;
}
.hot-card-big .video-card-thumb {
  aspect-ratio: 4/3;
}
.hot-card-big .video-card-title {
  font-size: 18px;
}

/* =========================================
   STRIP ANIMATION
   ========================================= */
.section-strip {
  background: linear-gradient(135deg, #EEF2FF 0%, #F3EEFF 50%, #FFF8EC 100%);
  overflow: hidden;
  padding: 16px 0;
  border-top: 1px solid var(--border-glow);
  border-bottom: 1px solid var(--border-glow);
  position: relative;
}
.section-strip::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--cyan), var(--purple), transparent);
  opacity: 0.5;
}
.strip-inner {
  display: flex;
  overflow: hidden;
  white-space: nowrap;
}
.strip-track {
  display: flex;
  align-items: center;
  gap: 0;
  animation: scrollStrip 30s linear infinite;
}
.strip-item {
  display: inline-flex;
  align-items: center;
  gap: 16px;
  padding: 0 32px;
  color: var(--text-secondary);
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 2px;
  text-transform: uppercase;
  white-space: nowrap;
  font-family: var(--font-display);
}
.strip-dot {
  width: 5px; height: 5px;
  background: var(--cyan);
  border-radius: 50%;
  flex-shrink: 0;
  box-shadow: 0 0 6px var(--cyan);
}
@keyframes scrollStrip {
  from { transform: translateX(0); }
  to { transform: translateX(-50%); }
}

/* =========================================
   FOOTER
   ========================================= */
.site-footer {
  background: linear-gradient(160deg, #EEF2FF 0%, #F3EEFF 60%, #FFF8EC 100%);
  border-top: 1px solid var(--border-glow);
  color: var(--text-secondary);
  padding: 72px 0 0;
  position: relative;
  overflow: hidden;
}
.site-footer::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--cyan), var(--purple), var(--orange), transparent);
  opacity: 0.4;
}
.site-footer::after {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse 55% 70% at 50% 120%, rgba(0,212,255,.06) 0%, transparent 65%);
  pointer-events: none;
}
/* 新居中品牌布局 */
.footer-brand-center {
  max-width: 640px;
  margin: 0 auto 44px;
  text-align: center;
  position: relative;
  z-index: 1;
}
.footer-logo {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 18px;
  color: var(--text-primary);
  font-size: 18px;
  font-weight: 700;
  font-family: var(--font-display);
  letter-spacing: .5px;
}
.footer-tagline {
  font-size: 15px;
  line-height: 1.75;
  color: var(--text-muted);
  max-width: 400px;
  margin: 0 auto 26px;
}
.footer-tagline em {
  font-style: normal;
  color: var(--cyan);
  font-weight: 600;
}
.footer-divider {
  width: 48px;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--cyan), var(--purple), transparent);
  margin: 0 auto 26px;
  border-radius: 2px;
}
.footer-social {
  display: flex;
  justify-content: center;
  gap: 12px;
}
.footer-social a {
  width: 40px; height: 40px;
  background: rgba(255,255,255,.7);
  border: 1px solid var(--border-dim);
  border-radius: 50%;
  display: grid; place-items: center;
  font-size: 15px;
  transition: var(--trans);
  color: var(--text-secondary);
}
.footer-social a:hover {
  background: white;
  border-color: var(--border-bright);
  color: var(--cyan);
  transform: translateY(-3px);
  box-shadow: 0 8px 20px rgba(0,212,255,.18);
}
.footer-bottom {
  max-width: 640px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 24px;
  padding: 24px 16px;
  font-size: 12px;
  color: var(--text-muted);
  border-top: 1px solid var(--border-dim);
  position: relative;
  z-index: 1;
  flex-wrap: wrap;
}
.footer-admin-link {
  color: var(--text-muted);
  font-size: 11px;
  transition: var(--trans);
}
.footer-admin-link:hover { color: var(--cyan); }

/* =========================================
   VIDEO MODAL
   ========================================= */
.video-modal {
  position: fixed;
  inset: 0;
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
}
.video-modal.active {
  opacity: 1;
  pointer-events: all;
}
.modal-overlay {
  position: absolute;
  inset: 0;
  background: rgba(26, 31, 60, 0.75);
  backdrop-filter: blur(6px);
}
.modal-content {
  position: relative;
  z-index: 1;
  background: var(--dark-panel);
  border: 1px solid var(--border-glow);
  border-radius: var(--radius-lg);
  overflow: hidden;
  width: 100%;
  max-width: 860px;
  max-height: 90vh;
  overflow-y: auto;
  box-shadow: 0 40px 80px rgba(0,0,0,0.8), var(--shadow-cyan);
  transform: translateY(20px) scale(0.97);
  transition: transform 0.3s ease;
}
.video-modal.active .modal-content {
  transform: translateY(0) scale(1);
}
.modal-close {
  position: absolute;
  top: 16px; right: 16px;
  z-index: 2;
  width: 36px; height: 36px;
  background: rgba(0,212,255,0.1);
  border: 1px solid var(--border-glow);
  border-radius: 8px;
  color: var(--text-secondary);
  font-size: 13px;
  display: flex; align-items: center; justify-content: center;
  transition: var(--trans);
}
.modal-close:hover {
  background: var(--cyan-subtle);
  color: var(--cyan);
  border-color: var(--border-bright);
}
.modal-video-wrap {
  background: #000;
  aspect-ratio: 16/9;
  position: relative;
}
.modal-video-wrap video {
  width: 100%; height: 100%;
  object-fit: contain;
}
.modal-info {
  padding: 24px 28px 28px;
}
.modal-meta {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 12px;
}
.modal-cat {
  padding: 3px 10px;
  border-radius: 3px;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 1px;
  text-transform: uppercase;
}
.modal-period {
  font-size: 11px;
  color: var(--text-muted);
}
#modalTitle {
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 8px;
  line-height: 1.3;
  letter-spacing: 0.3px;
}
.modal-student-info {
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 12px;
  display: flex; align-items: center; gap: 8px;
}
.modal-desc {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 20px;
  border-left: 2px solid var(--cyan);
  padding-left: 14px;
  background: rgba(0,212,255,0.03);
  padding-top: 8px;
  padding-bottom: 8px;
  border-radius: 0 4px 4px 0;
}
.modal-stats {
  display: flex;
  gap: 24px;
  font-size: 12px;
  color: var(--text-muted);
  margin-bottom: 20px;
}
.modal-stats span { display: flex; align-items: center; gap: 6px; }
.modal-actions {
  display: flex;
  gap: 12px;
}
.btn-download {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 22px;
  background: linear-gradient(135deg, var(--cyan), var(--purple));
  color: var(--space-black);
  font-size: 13px;
  font-weight: 700;
  border-radius: var(--radius);
  transition: var(--trans);
}
.btn-download:hover { filter: brightness(1.1); transform: translateY(-1px); }
.btn-share {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 18px;
  border: 1px solid var(--border-glow);
  color: var(--text-secondary);
  font-size: 13px;
  border-radius: var(--radius);
  transition: var(--trans);
  background: transparent;
}
.btn-share:hover {
  border-color: var(--border-bright);
  color: var(--cyan);
  background: var(--cyan-subtle);
}

/* =========================================
   PAGE HERO (videos.html)
   ========================================= */
.page-hero {
  padding: 140px 40px 70px;
  background: var(--space-black);
  position: relative;
  overflow: hidden;
}
.page-hero::before {
  content: '';
  position: absolute;
  top: -80px; right: -80px;
  width: 500px; height: 500px;
  background: radial-gradient(circle, rgba(0,212,255,0.10) 0%, transparent 65%);
}
.page-hero-inner {
  max-width: 1280px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
}
.page-hero-label {
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 4px;
  text-transform: uppercase;
  color: var(--cyan);
  margin-bottom: 16px;
  font-family: var(--font-display);
}
.page-hero-title {
  font-family: var(--font-display);
  font-size: clamp(32px, 5vw, 56px);
  font-weight: 900;
  color: var(--text-primary);
  margin-bottom: 12px;
  letter-spacing: -0.5px;
}
.page-hero-desc {
  font-size: 15px;
  color: var(--text-secondary);
}

/* =========================================
   FILTER BAR
   ========================================= */
.videos-section {
  padding: 60px 0 100px;
}
.filter-bar {
  display: flex;
  align-items: center;
  gap: 20px;
  margin-bottom: 32px;
  flex-wrap: wrap;
  background: var(--dark-panel);
  padding: 18px 22px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-dim);
  box-shadow: var(--shadow-sm);
}
.search-wrap {
  display: flex;
  align-items: center;
  gap: 10px;
  flex: 1;
  min-width: 200px;
  border: 1px solid var(--border-dim);
  border-radius: var(--radius);
  padding: 10px 14px;
  transition: var(--trans);
  background: var(--panel);
}
.search-wrap:focus-within {
  border-color: var(--border-bright);
  box-shadow: 0 0 0 3px rgba(0,212,255,0.08);
}
.search-wrap i { color: var(--text-muted); font-size: 13px; }
.search-wrap input {
  border: none;
  outline: none;
  font-size: 13px;
  width: 100%;
  color: var(--text-primary);
  background: transparent;
}
.search-wrap input::placeholder { color: var(--text-muted); }
.filter-tags {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}
.filter-tag {
  padding: 7px 15px;
  border: 1px solid var(--border-dim);
  border-radius: 100px;
  font-size: 12px;
  font-weight: 500;
  color: var(--text-secondary);
  transition: var(--trans);
  background: transparent;
}
.filter-tag:hover, .filter-tag.active {
  background: var(--cyan-subtle);
  border-color: var(--border-bright);
  color: var(--cyan);
}
.sort-wrap select {
  border: 1px solid var(--border-dim);
  border-radius: var(--radius);
  padding: 10px 14px;
  font-size: 12px;
  color: var(--text-primary);
  outline: none;
  background: var(--panel);
  cursor: pointer;
  transition: var(--trans);
}
.sort-wrap select:focus {
  border-color: var(--border-bright);
}
.results-info {
  font-size: 13px;
  color: var(--text-muted);
  margin-bottom: 28px;
}
.load-more-wrap {
  text-align: center;
  margin-top: 56px;
}
.btn-load-more {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 13px 34px;
  border: 1px solid var(--border-bright);
  color: var(--text-primary);
  font-size: 13px;
  font-weight: 500;
  border-radius: var(--radius);
  transition: var(--trans);
  background: transparent;
}
.btn-load-more:hover {
  background: var(--cyan-subtle);
  color: var(--cyan);
  box-shadow: var(--shadow-cyan);
}
.btn-load-more.loading {
  opacity: 0.5;
  pointer-events: none;
}

/* =========================================
   LOADING SKELETON
   ========================================= */
.skeleton {
  background: linear-gradient(90deg,
    var(--panel) 25%,
    var(--panel-light) 50%,
    var(--panel) 75%
  );
  background-size: 400% 100%;
  animation: shimmer 1.6s ease infinite;
  border-radius: var(--radius);
}
@keyframes shimmer {
  0% { background-position: 100% 0; }
  100% { background-position: -100% 0; }
}

/* =========================================
   TOAST
   ========================================= */
.toast {
  position: fixed;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%) translateY(80px);
  background: var(--dark-panel);
  border: 1px solid var(--border-glow);
  color: var(--text-primary);
  padding: 12px 24px;
  border-radius: 100px;
  font-size: 13px;
  font-weight: 500;
  z-index: 2000;
  transition: transform 0.3s ease;
  white-space: nowrap;
  box-shadow: var(--shadow-md);
  backdrop-filter: blur(12px);
}
.toast.show {
  transform: translateX(-50%) translateY(0);
}
.toast.success { border-color: rgba(0,212,255,0.4); box-shadow: var(--shadow-cyan); }
.toast.error   { border-color: rgba(255,107,53,0.4); box-shadow: var(--shadow-orange); }

/* =========================================
   RESPONSIVE
   ========================================= */
@media (max-width: 1200px) {
  /* 大平板：5列变3列 */
  .cat-banner-grid { grid-template-columns: repeat(3, 1fr); }
}
@media (max-width: 1024px) {
  .hero-content { grid-template-columns: 1fr; gap: 48px; }
  .hero-right { display: none; }
  /* 旧分类卡片兼容 */
  .cat-grid { grid-template-columns: repeat(2, 1fr); }
  .cat-grid-row2 .cat-card {
    flex: 0 0 calc(50% - 10px);
    max-width: calc(50% - 10px);
  }
  /* 新版 */
  .cat-banner-grid { grid-template-columns: repeat(2, 1fr); }
  .spotlight-layout { grid-template-columns: 1fr; }
  .spotlight-side { flex-direction: row; flex-wrap: wrap; gap: 14px; }
  .spotlight-side .video-card { flex: 1 1 calc(50% - 8px); }
  .hot-layout { grid-template-columns: 1fr; }
  .hot-card-big { grid-row: auto; }
  .footer-brand-center { padding: 0 20px; }
}
@media (max-width: 768px) {
  .main-nav, .header-actions .btn-admin { display: none; }
  .mobile-menu-btn { display: block; margin-left: auto; }
  .hero-stats { gap: 20px; }
  .stat-num { font-size: 28px; }
  /* 旧卡片兼容 */
  .cat-grid,
  .cat-grid-row2 { grid-template-columns: 1fr; }
  .cat-grid-row2 .cat-card {
    flex: 0 0 100%;
    max-width: 100%;
  }
  /* 新版 */
  .cat-banner-grid { grid-template-columns: repeat(2, 1fr); gap: 12px; }
  .cat-banner { padding: 24px 18px 20px; }
  .cb-num { font-size: 26px; }
  .spotlight-side .video-card { flex: 1 1 100%; }
  .section-header-v2 { flex-direction: column; align-items: flex-start; }
  .shv2-more { margin-top: 4px; }
  .video-grid { grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 18px; }
  .footer-brand-center { padding: 0 16px; }
  .filter-bar { flex-direction: column; align-items: stretch; }
  .section-header { flex-direction: column; align-items: flex-start; }
}
@media (max-width: 480px) {
  .cat-banner-grid { grid-template-columns: 1fr; }
  .spotlight-layout { gap: 16px; }
  .shv2-title { font-size: 22px; }
  .latest-track .video-card { flex: 0 0 260px; width: 260px; }
}

/* =========================================
   HERO SEARCH — 空白提示
   ========================================= */
@keyframes heroSearchShake {
  0%, 100% { transform: translateX(0); }
  15%       { transform: translateX(-7px); }
  35%       { transform: translateX(7px); }
  55%       { transform: translateX(-5px); }
  75%       { transform: translateX(5px); }
  90%       { transform: translateX(-2px); }
}
.hero-search-shake {
  animation: heroSearchShake 0.45s ease;
  border-color: #ef4444 !important;
  box-shadow: 0 0 0 3px rgba(239,68,68,0.18) !important;
}

/* 气泡提示 */
.hero-search-tip {
  position: absolute;
  bottom: calc(100% + 10px);
  left: 50%;
  transform: translateX(-50%) translateY(6px);
  background: #1e1e2e;
  color: #fca5a5;
  font-size: 13px;
  font-weight: 500;
  padding: 8px 16px;
  border-radius: 8px;
  border: 1px solid rgba(239,68,68,0.4);
  white-space: nowrap;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.22s ease, transform 0.22s ease;
  z-index: 50;
  box-shadow: 0 4px 16px rgba(0,0,0,0.25);
}
.hero-search-tip::after {
  content: '';
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%);
  border: 6px solid transparent;
  border-top-color: rgba(239,68,68,0.4);
}
.hero-search-tip.visible {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}