/* ============================================
   赵爱林学习平台 - 高端设计系统 v3
   ============================================ */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&display=swap');

:root {
  /* === 基础色板 === */
  --bg-deep:      #060810;
  --bg-primary:   #0b0f1a;
  --bg-secondary: #101624;
  --bg-card:      #141b2d;
  --bg-card-2:    #1a2340;
  --bg-hover:     #1e2a45;
  --bg-glass:     rgba(20, 27, 45, 0.7);

  /* === 品牌渐变 === */
  --blue:         #4f8ef7;
  --blue-light:   #7eb3ff;
  --purple:       #a78bfa;
  --cyan:         #22d3ee;
  --green:        #34d399;
  --orange:       #fbbf24;
  --red:          #f87171;

  --grad-brand:   linear-gradient(135deg, #4f8ef7 0%, #a78bfa 100%);
  --grad-brand-h: linear-gradient(135deg, #6fa8ff 0%, #c4b5fd 100%);
  --grad-cyan:    linear-gradient(135deg, #22d3ee 0%, #4f8ef7 100%);
  --grad-green:   linear-gradient(135deg, #34d399 0%, #22d3ee 100%);
  --grad-warm:    linear-gradient(135deg, #fbbf24 0%, #f87171 100%);
  --grad-hero:    linear-gradient(160deg, #0b0f1a 0%, #0f1629 50%, #0b0f1a 100%);

  /* === 文字 === */
  --text-primary:   #f0f4ff;
  --text-secondary: #8b9dc3;
  --text-muted:     #4a5880;
  --text-dim:       #2d3a56;

  /* === 边框 === */
  --border:         rgba(255,255,255,0.06);
  --border-bright:  rgba(255,255,255,0.12);
  --border-blue:    rgba(79,142,247,0.4);

  /* === 光效 / 阴影 === */
  --glow-blue:    0 0 30px rgba(79,142,247,0.25);
  --glow-purple:  0 0 30px rgba(167,139,250,0.25);
  --shadow-sm:    0 2px 8px rgba(0,0,0,0.4);
  --shadow-md:    0 8px 32px rgba(0,0,0,0.5);
  --shadow-lg:    0 20px 60px rgba(0,0,0,0.6);
  --shadow-card:  0 4px 24px rgba(0,0,0,0.45), 0 1px 4px rgba(0,0,0,0.3);

  /* === 形状 & 动效 === */
  --radius-sm:  8px;
  --radius:     14px;
  --radius-lg:  20px;
  --radius-xl:  28px;
  --transition: all 0.25s cubic-bezier(0.4,0,0.2,1);
  --transition-slow: all 0.45s cubic-bezier(0.4,0,0.2,1);
}

/* === 亮色主题（护眼模式） === */
[data-theme="light"] {
  --bg-deep:      #f5f3f0;
  --bg-primary:   #faf9f7;
  --bg-secondary: #f0ede8;
  --bg-card:      #ffffff;
  --bg-card-2:    #f8f6f2;
  --bg-hover:     #f0ebe5;
  --bg-glass:     rgba(255, 255, 255, 0.85);

  --text-primary:   #2d3748;
  --text-secondary: #5a6578;
  --text-muted:     #8b95a5;
  --text-dim:       #c5cad3;

  --border:         rgba(0,0,0,0.06);
  --border-bright:  rgba(0,0,0,0.1);
  --border-blue:    rgba(79,142,247,0.5);

  --grad-hero:    linear-gradient(160deg, #faf9f7 0%, #f5f3f0 50%, #faf9f7 100%);
}

/* 护眼模式（暖色调） */
[data-theme="warm"] {
  --bg-deep:      #faf5eb;
  --bg-primary:   #fcf8f0;
  --bg-secondary: #f5efe4;
  --bg-card:      #fffbf5;
  --bg-card-2:    #f8f3e8;
  --bg-hover:     #f0e8d8;
  --bg-glass:     rgba(255, 251, 245, 0.9);

  --text-primary:   #4a4035;
  --text-secondary: #7a6e5f;
  --text-muted:     #a89b8a;
  --text-dim:       #d4cabb;

  --border:         rgba(139, 115, 85, 0.08);
  --border-bright:  rgba(139, 115, 85, 0.15);
  --border-blue:    rgba(79,142,247,0.5);

  --grad-brand:   linear-gradient(135deg, #e8a040 0%, #d4845a 100%);
  --grad-hero:    linear-gradient(160deg, #fcf8f0 0%, #faf5eb 50%, #fcf8f0 100%);
}

/* ============================================
   基础重置
   ============================================ */
*, *::before, *::after {
  margin: 0; padding: 0; box-sizing: border-box;
}

html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', 'PingFang SC', 'Noto Sans SC', 'Microsoft YaHei', sans-serif;
  background: var(--bg-deep);
  color: var(--text-primary);
  line-height: 1.65;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
  transition: background-color 0.4s ease, color 0.4s ease;
}

/* ============================================
   全局背景网格纹理
   ============================================ */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  background-image:
    linear-gradient(rgba(79,142,247,0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(79,142,247,0.03) 1px, transparent 1px);
  background-size: 40px 40px;
  pointer-events: none;
  z-index: 0;
}

/* ============================================
   Header — 顶部导航栏
   ============================================ */
.header {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: 68px;
  background: rgba(6, 8, 16, 0.85);
  backdrop-filter: blur(24px) saturate(180%);
  -webkit-backdrop-filter: blur(24px) saturate(180%);
  border-bottom: 1px solid var(--border);
  z-index: 1000;
  transition: var(--transition);
}

.header::after {
  content: '';
  position: absolute;
  bottom: 0; left: 0; right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent 0%, rgba(79,142,247,0.5) 30%, rgba(167,139,250,0.5) 70%, transparent 100%);
}

.header.scrolled {
  box-shadow: 0 4px 20px rgba(0,0,0,0.3);
}

.header-content {
  max-width: 1440px;
  margin: 0 auto;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 32px;
  gap: 16px;
}

/* Logo */
.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.25rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  text-decoration: none;
  flex-shrink: 0;
}

.logo i {
  font-size: 1.5rem;
  background: var(--grad-brand);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  filter: drop-shadow(0 0 8px rgba(79,142,247,0.5));
}

#siteName {
  background: linear-gradient(135deg, #f0f4ff 0%, #8b9dc3 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* ============================================
   Header 精致倒计时 - 和标题并排
   ============================================ */
.header-countdown {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 8px 16px;
  background: linear-gradient(135deg, rgba(79,142,247,0.1) 0%, rgba(167,139,250,0.1) 100%);
  border: 1px solid rgba(79,142,247,0.25);
  border-radius: 50px;
  backdrop-filter: blur(10px);
  flex-shrink: 0;
}

.countdown-label-inline {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.78rem;
  color: var(--text-secondary);
  white-space: nowrap;
}

.countdown-label-inline i {
  color: var(--orange);
  font-size: 0.85rem;
  animation: pulse-glow 2s ease-in-out infinite;
}

@keyframes pulse-glow {
  0%, 100% { 
    opacity: 0.8;
    filter: drop-shadow(0 0 4px rgba(251,191,36,0.5));
  }
  50% { 
    opacity: 1;
    filter: drop-shadow(0 0 8px rgba(251,191,36,0.8));
  }
}

.countdown-timer-inline {
  display: flex;
  align-items: center;
  gap: 4px;
}

.countdown-unit-inline {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-width: 36px;
  background: rgba(79,142,247,0.15);
  border-radius: 8px;
  padding: 4px 6px;
  border: 1px solid rgba(79,142,247,0.2);
}

.countdown-value-inline {
  font-size: 1.1rem;
  font-weight: 800;
  font-family: 'JetBrains Mono', 'Courier New', monospace;
  color: #ffffff;
  text-shadow: 0 0 10px rgba(168, 200, 255, 0.5), 0 2px 4px rgba(0, 0, 0, 0.3);
  line-height: 1.1;
  letter-spacing: -1px;
}

.countdown-name-inline {
  font-size: 0.6rem;
  color: var(--text-muted);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.countdown-sep-inline {
  font-size: 1rem;
  font-weight: 700;
  color: var(--blue);
  animation: blink-sep 1s step-end infinite;
  margin-bottom: 6px;
}

@keyframes blink-sep {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.3; }
}

/* 手机端隐藏 header 倒计时 */
@media (max-width: 1024px) {
  .header-countdown {
    display: none;
  }
}

/* 桌面导航 */
.nav {
  display: flex;
  align-items: center;
  gap: 4px;
  background: rgba(255,255,255,0.03);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: 5px;
}

.nav-item {
  padding: 8px 20px;
  color: var(--text-secondary);
  text-decoration: none;
  border-radius: 20px;
  transition: var(--transition);
  display: flex;
  align-items: center;
  gap: 7px;
  font-size: 0.9rem;
  font-weight: 500;
  white-space: nowrap;
}

.nav-item:hover {
  color: var(--text-primary);
  background: rgba(255,255,255,0.06);
}

.nav-item.active {
  background: var(--grad-brand);
  color: white;
  box-shadow: 0 2px 12px rgba(79,142,247,0.35);
}

/* 用户区域 */
.user-section {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
}

.btn-login {
  padding: 9px 22px;
  background: var(--grad-brand);
  color: white;
  border: none;
  border-radius: 22px;
  cursor: pointer;
  font-size: 0.88rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 7px;
  transition: var(--transition);
  box-shadow: 0 2px 12px rgba(79,142,247,0.3);
  white-space: nowrap;
}

.btn-login:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(79,142,247,0.45);
}

.admin-link {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 9px 18px;
  color: var(--purple);
  text-decoration: none;
  border-radius: 22px;
  border: 1px solid rgba(167,139,250,0.3);
  transition: var(--transition);
  font-size: 0.88rem;
  font-weight: 500;
  background: rgba(167,139,250,0.05);
}

.admin-link:hover {
  background: rgba(167,139,250,0.15);
  border-color: var(--purple);
  box-shadow: 0 0 20px rgba(167,139,250,0.2);
}

/* ============================================
   头部操作区 & 主题切换器
   ============================================ */
.header-actions {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
}

.theme-switcher {
  display: flex;
  align-items: center;
  gap: 4px;
  background: rgba(255,255,255,0.03);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 4px;
  position: relative;
}

.theme-btn {
  padding: 7px 10px;
  background: transparent;
  border: none;
  border-radius: 16px;
  cursor: pointer;
  color: var(--text-muted);
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  z-index: 2;
}

.theme-btn:hover {
  color: var(--text-primary);
}

.theme-btn.active {
  color: var(--blue);
}

.theme-btn i {
  font-size: 0.85rem;
}

.theme-indicator {
  position: absolute;
  height: calc(100% - 8px);
  background: rgba(79,142,247,0.15);
  border-radius: 16px;
  transition: all 0.3s cubic-bezier(0.4,0,0.2,1);
  z-index: 1;
}

/* 深色主题指示器位置 */
[data-theme-settings="dark"] ~ .theme-switcher .theme-indicator,
html[data-theme="dark"] .theme-switcher .theme-indicator {
  left: 6px;
  width: calc(33.33% - 4px);
}
[data-theme-settings="light"] ~ .theme-switcher .theme-indicator,
html[data-theme="light"] .theme-switcher .theme-indicator {
  left: calc(33.33% + 2px);
  width: calc(33.33% - 4px);
}
[data-theme-settings="warm"] ~ .theme-switcher .theme-indicator,
html[data-theme="warm"] .theme-switcher .theme-indicator {
  left: calc(66.66% - 2px);
  width: calc(33.33% - 4px);
}

.user-info {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 6px 14px 6px 8px;
  background: var(--bg-card);
  border-radius: 28px;
  border: 1px solid var(--border);
}

.user-info .avatar {
  width: 34px;
  height: 34px;
  background: var(--grad-brand);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: 700;
  font-size: 0.85rem;
  flex-shrink: 0;
  box-shadow: 0 0 12px rgba(79,142,247,0.4);
}

.btn-logout {
  padding: 8px 16px;
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-secondary);
  border-radius: 20px;
  cursor: pointer;
  transition: var(--transition);
  font-size: 0.85rem;
  white-space: nowrap;
}

.btn-logout:hover {
  border-color: var(--red);
  color: var(--red);
  background: rgba(248,113,113,0.08);
}

/* ============================================
   主内容区域
   ============================================ */
.main-content {
  padding-top: 68px;
  min-height: 100vh;
  position: relative;
  z-index: 1;
}

.page {
  animation: pageIn 0.35s cubic-bezier(0.4,0,0.2,1);
}

.page.hidden { display: none; }

@keyframes pageIn {
  from { opacity: 0; transform: translateY(16px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ============================================
   Hero 区域 — 首页横幅
   ============================================ */
.hero {
  position: relative;
  min-height: 560px;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  padding: 60px 20px;
}

/* 背景光晕 */
.hero-bg {
  position: absolute;
  inset: 0;
  background: var(--grad-hero);
}

.hero-bg::before {
  content: '';
  position: absolute;
  width: 700px; height: 700px;
  left: -150px; top: -200px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(79,142,247,0.12) 0%, transparent 70%);
  animation: heroPulse 8s ease-in-out infinite;
}

.hero-bg::after {
  content: '';
  position: absolute;
  width: 600px; height: 600px;
  right: -100px; bottom: -150px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(167,139,250,0.1) 0%, transparent 70%);
  animation: heroPulse 8s ease-in-out infinite reverse;
}

@keyframes heroPulse {
  0%, 100% { transform: scale(1) translate(0, 0); }
  33%  { transform: scale(1.1) translate(20px, -20px); }
  66%  { transform: scale(0.95) translate(-10px, 15px); }
}

/* 网格装饰线 */
.hero-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(79,142,247,0.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(79,142,247,0.06) 1px, transparent 1px);
  background-size: 80px 80px;
  mask-image: radial-gradient(ellipse 80% 80% at 50% 50%, black 20%, transparent 100%);
}

.hero-content {
  position: relative;
  text-align: center;
  z-index: 2;
  max-width: 800px;
}

/* 标签胶囊 */
.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  background: rgba(79,142,247,0.1);
  border: 1px solid rgba(79,142,247,0.3);
  border-radius: 20px;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--blue-light);
  letter-spacing: 0.04em;
  text-transform: uppercase;
  margin-bottom: 24px;
}

.hero-badge::before {
  content: '';
  width: 6px; height: 6px;
  border-radius: 50%;
  background: var(--cyan);
  box-shadow: 0 0 6px var(--cyan);
  animation: blink 1.5s ease-in-out infinite;
}

@keyframes blink {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.3; }
}

.hero-title {
  font-size: 4rem;
  font-weight: 900;
  line-height: 1.1;
  letter-spacing: -0.03em;
  margin-bottom: 20px;
}

.hero-title .line1 {
  display: block;
  background: linear-gradient(135deg, #ffffff 0%, #c8d8ff 60%, #a78bfa 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-title .line2 {
  display: block;
  background: var(--grad-brand);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  filter: drop-shadow(0 0 30px rgba(79,142,247,0.4));
}

.hero-subtitle {
  font-size: 1.05rem;
  color: var(--text-secondary);
  margin-bottom: 40px;
  line-height: 1.8;
}

.hero-stats {
  display: flex;
  gap: 0;
  justify-content: center;
  margin-bottom: 44px;
  background: rgba(255,255,255,0.03);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 20px 0;
  backdrop-filter: blur(10px);
  max-width: 400px;
  margin-left: auto;
  margin-right: auto;
}

.stat-item {
  flex: 1;
  text-align: center;
  position: relative;
}

.stat-item + .stat-item::before {
  content: '';
  position: absolute;
  left: 0; top: 20%; bottom: 20%;
  width: 1px;
  background: var(--border-bright);
}

.stat-number {
  display: block;
  font-size: 2.2rem;
  font-weight: 900;
  letter-spacing: -0.03em;
  background: var(--grad-brand);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 4px;
}

.stat-label {
  font-size: 0.82rem;
  color: var(--text-muted);
  font-weight: 500;
}

.btn-primary {
  padding: 15px 40px;
  background: var(--grad-brand);
  color: white;
  border: none;
  border-radius: 50px;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 10px;
  transition: var(--transition);
  box-shadow: 0 4px 20px rgba(79,142,247,0.4), 0 0 0 0 rgba(79,142,247,0);
  letter-spacing: 0.01em;
}

.btn-primary:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 32px rgba(79,142,247,0.55), 0 0 0 4px rgba(79,142,247,0.1);
}

.btn-primary:active {
  transform: translateY(-1px);
}

/* ============================================
   首页课程展示区域 — 自动排版
   ============================================ */
.home-courses-section {
  max-width: 1440px;
  margin: 0 auto;
  padding: 40px 32px 60px;
}

.courses-preview-container {
  width: 100%;
}

/* 自适应课程网格 — 自动排版，无论多少课程都能完美展示 */
.courses-grid {
  display: grid;
  /* 自动填充，每列最小 380px，最大平分空间 */
  grid-template-columns: repeat(auto-fill, minmax(380px, 1fr));
  gap: 24px;
}

/* 课程网格响应式：小屏幕时单列显示 */
@media (max-width: 768px) {
  .home-courses-section {
    padding: 24px 14px 40px;
  }
  
  .courses-grid {
    grid-template-columns: 1fr;
    gap: 16px;
  }
}

/* 大屏幕时最多显示 4 列 */
@media (min-width: 1400px) {
  .courses-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

/* 超大屏幕时最多显示 4 列 */
@media (min-width: 1800px) {
  .courses-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

.section-title {
  font-size: 1.6rem;
  font-weight: 800;
  margin-bottom: 32px;
  display: flex;
  align-items: center;
  gap: 12px;
  letter-spacing: -0.02em;
}

.section-title i {
  background: var(--grad-brand);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* 全部课程区域 */
.courses-section {
  max-width: 1440px;
  margin: 0 auto;
  padding: 0 32px 60px;
}

.courses-section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 24px;
}

.courses-section-title {
  font-size: 1.4rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 0;
}

.courses-section-title i {
  background: var(--grad-brand);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.courses-section-more {
  color: var(--blue);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  border-radius: 20px;
  background: rgba(79,142,247,0.08);
  border: 1px solid rgba(79,142,247,0.2);
  transition: var(--transition);
}

.courses-section-more:hover {
  background: rgba(79,142,247,0.15);
  border-color: rgba(79,142,247,0.4);
  transform: translateX(4px);
}

@media (max-width: 768px) {
  .courses-section {
    padding: 0 14px 60px;
  }
  
  .courses-section-header {
    margin-bottom: 16px;
  }
  
  .courses-section-title {
    font-size: 1.15rem;
  }
}

/* ============================================
   课程卡片 — 高端玻璃态
   ============================================ */
.course-card {
  background: var(--bg-card);
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--border);
  transition: var(--transition);
  cursor: pointer;
  position: relative;
  box-shadow: var(--shadow-card);
}

.course-card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: var(--radius-lg);
  background: linear-gradient(135deg, rgba(79,142,247,0.04) 0%, transparent 50%);
  opacity: 0;
  transition: var(--transition);
}

.course-card:hover {
  transform: translateY(-6px);
  border-color: rgba(79,142,247,0.35);
  box-shadow: var(--shadow-lg), 0 0 0 1px rgba(79,142,247,0.15);
}

.course-card:hover::before {
  opacity: 1;
}

.course-card-header {
  padding: 32px 30px 24px;
  position: relative;
  overflow: hidden;
  min-height: 160px;
}

.course-card-header::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, var(--card-color, var(--blue)) 0%, transparent 60%);
  opacity: 0.18;
}

.course-card-header::after {
  content: '';
  position: absolute;
  right: -20px; top: -20px;
  width: 120px; height: 120px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(255,255,255,0.07) 0%, transparent 70%);
}

.course-icon {
  font-size: 2.8rem;
  margin-bottom: 14px;
  display: block;
  position: relative;
  z-index: 1;
  filter: drop-shadow(0 4px 8px rgba(0,0,0,0.3));
}

.course-card-header h3 {
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 6px;
  letter-spacing: -0.02em;
  position: relative;
  z-index: 1;
}

.course-card-header p {
  color: var(--text-secondary);
  font-size: 0.88rem;
  position: relative;
  z-index: 1;
}

.course-card-body {
  padding: 20px 30px 26px;
  border-top: 1px solid var(--border);
}

.course-meta {
  display: flex;
  gap: 16px;
  color: var(--text-muted);
  font-size: 0.85rem;
  margin-bottom: 16px;
  flex-wrap: wrap;
}

.course-meta span {
  display: flex;
  align-items: center;
  gap: 5px;
  padding: 4px 10px;
  background: rgba(255,255,255,0.04);
  border-radius: 20px;
  border: 1px solid var(--border);
}

.course-meta span i {
  color: var(--blue);
}

.course-progress {
  background: rgba(255,255,255,0.05);
  border-radius: 6px;
  height: 6px;
  overflow: hidden;
  position: relative;
}

.course-progress::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, rgba(255,255,255,0.03) 25%, rgba(255,255,255,0.08) 50%, rgba(255,255,255,0.03) 75%);
  background-size: 200% 100%;
  animation: shimmer 2s linear infinite;
}

@keyframes shimmer {
  from { background-position: 200% 0; }
  to   { background-position: -200% 0; }
}

.course-progress-fill {
  height: 100%;
  background: var(--grad-brand);
  border-radius: 6px;
  transition: width 0.8s cubic-bezier(0.4,0,0.2,1);
  position: relative;
  z-index: 1;
}

.course-progress-text {
  text-align: right;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 8px;
}

.preview-notice {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px;
  background: rgba(79,142,247,0.07);
  border: 1px dashed rgba(79,142,247,0.25);
  border-radius: var(--radius-sm);
  color: var(--blue);
  font-size: 0.85rem;
  margin-top: 12px;
}

/* ============================================
   页面通用头部
   ============================================ */
.page-header {
  max-width: 1200px;
  margin: 0 auto;
  padding: 36px 32px 20px;
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

.page-header h2 {
  font-size: 1.6rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  display: flex;
  align-items: center;
  gap: 12px;
}

.page-header h2 i {
  background: var(--grad-brand);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.btn-back {
  padding: 9px 18px;
  background: rgba(255,255,255,0.04);
  border: 1px solid var(--border-bright);
  color: var(--text-secondary);
  border-radius: 22px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 7px;
  transition: var(--transition);
  font-size: 0.88rem;
  font-weight: 500;
  white-space: nowrap;
}

.btn-back:hover {
  border-color: var(--blue);
  color: var(--text-primary);
  background: rgba(79,142,247,0.1);
}

/* ============================================
   课程详情 — 章节列表
   ============================================ */
.course-content {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 32px 80px;
}

.chapter-item {
  background: var(--bg-card);
  border-radius: var(--radius);
  margin-bottom: 16px;
  overflow: hidden;
  border: 1px solid var(--border);
  transition: var(--transition);
}

.chapter-item:hover {
  border-color: var(--border-bright);
}

.chapter-header {
  padding: 18px 22px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  transition: var(--transition);
  user-select: none;
}

.chapter-header:hover {
  background: rgba(255,255,255,0.03);
}

.chapter-header h4 {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
}

.chapter-header h4 i {
  color: var(--blue);
  font-size: 0.9rem;
}

.chapter-toggle {
  color: var(--text-muted);
  transition: var(--transition);
  font-size: 0.85rem;
}

.chapter-item.expanded .chapter-toggle {
  transform: rotate(180deg);
  color: var(--blue);
}

.chapter-lessons {
  display: none;
  padding: 0 16px 16px;
}

.chapter-item.expanded .chapter-lessons {
  display: block;
}

.lesson-item {
  display: flex;
  align-items: center;
  padding: 14px 16px;
  background: rgba(255,255,255,0.02);
  border-radius: var(--radius-sm);
  margin-top: 8px;
  cursor: pointer;
  transition: var(--transition);
  gap: 14px;
  border: 1px solid transparent;
}

.lesson-item:hover {
  background: var(--bg-hover);
  border-color: var(--border-blue);
  transform: translateX(4px);
}

.lesson-item.completed {
  border-left: 3px solid var(--green);
}

.lesson-item .lesson-icon {
  width: 36px;
  height: 36px;
  background: var(--grad-brand);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  flex-shrink: 0;
  font-size: 0.82rem;
  font-weight: 700;
  box-shadow: 0 2px 8px rgba(79,142,247,0.3);
}

.lesson-item.completed .lesson-icon {
  background: linear-gradient(135deg, var(--green) 0%, var(--cyan) 100%);
  box-shadow: 0 2px 8px rgba(52,211,153,0.3);
}

.lesson-info {
  flex: 1;
  min-width: 0;
}

.lesson-info h5 {
  font-size: 0.9rem;
  font-weight: 500;
  margin-bottom: 3px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.lesson-info span {
  font-size: 0.8rem;
  color: var(--text-muted);
}

.lesson-status {
  color: var(--green);
  font-size: 0.9rem;
}

.lesson-lock {
  color: var(--text-dim);
  font-size: 0.85rem;
  margin-left: auto;
}

/* ============================================
   视频播放页 — 核心布局
   ============================================ */
.video-page-wrapper {
  display: flex;
  gap: 0;
  height: calc(100vh - 68px);
  max-width: 100%;
  overflow: hidden;
}

.video-left {
  flex: 1;
  min-width: 0;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  background: var(--bg-deep);
}

.video-right {
  width: 360px;
  flex-shrink: 0;
  display: flex;
  flex-direction: column;
  background: var(--bg-card);
  border-left: 1px solid var(--border);
  overflow: hidden;
}

/* 视频头部 */
.video-header {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 12px 20px;
  background: rgba(6,8,16,0.8);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

.video-title-info {
  flex: 1;
  min-width: 0;
}

.video-title-info h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 2px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.video-title-info p {
  color: var(--text-muted);
  font-size: 0.8rem;
}

/* 视频播放主区域 */
.video-main {
  flex: 1;
  display: flex;
  flex-direction: column;
  background: #000;
  overflow: hidden;
}

/* ============================================
   Plyr 播放器主题适配
   ============================================ */

/* 深色主题（默认）- Plyr 变量覆盖 */
[data-theme="dark"] {
  --plyr-color-main: #4f8ef7;
  --plyr-video-background: rgba(0, 0, 0, 0.9);
  --plyr-range-fill-background: #4f8ef7;
  --plyr-video-control-color: #fff;
  --plyr-video-control-background-hover: rgba(79, 142, 247, 0.3);
}

/* 护眼主题 - Plyr 变量覆盖 */
[data-theme="light"] {
  --plyr-color-main: #4f8ef7;
  --plyr-video-background: rgba(250, 249, 247, 0.95);
  --plyr-range-fill-background: #4f8ef7;
  --plyr-video-control-color: #333;
  --plyr-video-control-background-hover: rgba(79, 142, 247, 0.2);
  --plyr-video-text-track-background: rgba(0, 0, 0, 0.5);
  --plyr-captions-background: rgba(0, 0, 0, 0.8);
}

/* 暖色主题 - Plyr 变量覆盖 */
[data-theme="warm"] {
  --plyr-color-main: #e8a040;
  --plyr-video-background: rgba(252, 248, 240, 0.95);
  --plyr-range-fill-background: #e8a040;
  --plyr-video-control-color: #5a4a3a;
  --plyr-video-control-background-hover: rgba(232, 160, 64, 0.25);
  --plyr-video-text-track-background: rgba(90, 74, 58, 0.5);
  --plyr-captions-background: rgba(90, 74, 58, 0.9);
}

/* Plyr 容器样式 */
.video-wrapper {
  position: relative;
}

/* 只在 Plyr 激活时隐藏原生控件 */
.plyr video::-webkit-media-controls {
  display: none !important;
}
.plyr video::-webkit-media-controls-enclosure {
  display: none !important;
}

/* Plyr 大播放按钮美化 */
.plyr--video .plyr__control.plyr__tab-focus,
.plyr--video .plyr__control:hover,
.plyr--video .plyr__control:focus {
  background: var(--plyr-color-main);
}

/* Plyr 进度条美化 */
.plyr--video .plyr__progress__buffer {
  color: rgba(255, 255, 255, 0.25);
}

/* Plyr 控制栏高度和样式 */
.plyr--video .plyr__controls {
  background: linear-gradient(transparent, rgba(0, 0, 0, 0.8));
  padding: 40px 12px 12px;
}

/* 护眼模式控制栏 */
[data-theme="light"] .plyr--video .plyr__controls {
  background: linear-gradient(transparent, rgba(250, 249, 247, 0.95));
}

/* 暖色模式控制栏 */
[data-theme="warm"] .plyr--video .plyr__controls {
  background: linear-gradient(transparent, rgba(252, 248, 240, 0.95));
}

/* Plyr 工具提示 */
.plyr__tooltip {
  background: rgba(0, 0, 0, 0.8);
  border-radius: 4px;
  font-size: 12px;
}

/* 护眼模式工具提示 */
[data-theme="light"] .plyr__tooltip {
  background: rgba(255, 255, 255, 0.95);
  color: #333;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

/* 暖色模式工具提示 */
[data-theme="warm"] .plyr__tooltip {
  background: rgba(252, 248, 240, 0.98);
  color: #5a4a3a;
  box-shadow: 0 2px 8px rgba(139, 115, 85, 0.15);
}

/* Plyr 设置菜单 */
.plyr--video .plyr__menu__container {
  background: rgba(0, 0, 0, 0.85);
  border-radius: 8px;
}

/* Plyr 加载动画 */
.plyr--loading .plyr__loader {
  border-color: var(--plyr-color-main);
  border-right-color: transparent;
}

/* Plyr 画中画按钮 */
.plyr--pip-supported .plyr__control--overlaid {
  display: flex;
}

/* 全屏时的 Plyr 样式 */
.plyr:fullscreen .plyr__video-wrapper {
  background: #000;
}

/* 视频 wrapper */
.video-wrapper {
  flex: 1;
  background: #000;
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.video-wrapper video {
  width: 100%;
  height: 100%;
  object-fit: contain;
  background: #000;
}

/* 视频加载占位 */
.video-placeholder {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: radial-gradient(ellipse at center, #0d1525 0%, #060810 100%);
  color: var(--text-muted);
  gap: 0;
  text-align: center;
  padding: 24px;
}

.video-placeholder i {
  font-size: 2.8rem;
  margin-bottom: 14px;
  opacity: 0.6;
  color: var(--blue);
}

.video-placeholder i:not(.fa-spin) {
  animation: pulse 2.5s ease-in-out infinite;
}

.video-placeholder p {
  margin: 0 0 16px;
  font-size: 0.9rem;
  line-height: 1.7;
  max-width: 260px;
}

@keyframes pulse {
  0%, 100% { opacity: 0.3; transform: scale(1); }
  50% { opacity: 0.8; transform: scale(1.05); }
}

/* 视频进度条 */
.video-progress-container {
  padding: 10px 16px;
  background: rgba(6,8,16,0.9);
  border-top: 1px solid var(--border);
  flex-shrink: 0;
  display: flex;
  align-items: center;
  gap: 12px;
}

.video-progress-bar {
  background: rgba(255,255,255,0.08);
  height: 4px;
  border-radius: 2px;
  overflow: hidden;
  flex: 1;
}

.progress-fill {
  height: 100%;
  background: var(--grad-brand);
  border-radius: 2px;
  width: 0%;
  transition: width 0.4s ease;
  box-shadow: 0 0 8px rgba(79,142,247,0.5);
}

/* 视频倍速控制器 */
.speed-control {
  display: flex;
  align-items: center;
  gap: 6px;
  flex-shrink: 0;
}

.speed-btn {
  padding: 4px 10px;
  background: rgba(255,255,255,0.08);
  border: 1px solid rgba(255,255,255,0.12);
  border-radius: 14px;
  color: var(--text-secondary);
  font-size: 0.78rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  white-space: nowrap;
}

.speed-btn:hover {
  background: rgba(79,142,247,0.2);
  border-color: var(--blue);
  color: var(--blue);
}

.speed-btn.active {
  background: var(--grad-brand);
  border-color: transparent;
  color: white;
}

/* 音量控制 */
.volume-control {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
}

.volume-btn {
  padding: 6px;
  background: transparent;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
}

.volume-btn:hover {
  color: var(--text-primary);
}

.volume-slider {
  width: 70px;
  height: 4px;
  -webkit-appearance: none;
  appearance: none;
  background: rgba(255,255,255,0.15);
  border-radius: 2px;
  cursor: pointer;
}

.volume-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 12px;
  height: 12px;
  background: var(--blue);
  border-radius: 50%;
  cursor: pointer;
  box-shadow: 0 0 6px rgba(79,142,247,0.5);
}

.volume-slider::-moz-range-thumb {
  width: 12px;
  height: 12px;
  background: var(--blue);
  border-radius: 50%;
  cursor: pointer;
  border: none;
  box-shadow: 0 0 6px rgba(79,142,247,0.5);
}

/* 播放列表目录（右侧） */
.playlist-header {
  padding: 16px 18px;
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

.playlist-header h4 {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 8px;
}

.playlist-header h4 i {
  color: var(--blue);
}

.playlist-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.btn-favorite {
  padding: 8px 14px;
  background: rgba(255,255,255,0.06);
  border: 1px solid var(--border);
  border-radius: 20px;
  color: var(--text-muted);
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.82rem;
}

.btn-favorite:hover {
  background: rgba(248,113,113,0.1);
  border-color: rgba(248,113,113,0.3);
  color: var(--red);
}

.btn-favorite.active {
  background: rgba(248,113,113,0.15);
  border-color: var(--red);
  color: var(--red);
}

.btn-favorite.active i {
  animation: heartBeat 0.6s ease;
}

@keyframes heartBeat {
  0% { transform: scale(1); }
  25% { transform: scale(1.3); }
  50% { transform: scale(1); }
  75% { transform: scale(1.2); }
  100% { transform: scale(1); }
}

/* 课程卡片收藏按钮 */
.course-card-actions {
  position: absolute;
  top: 12px;
  right: 12px;
  z-index: 5;
}

.btn-favorite-card {
  width: 36px;
  height: 36px;
  background: rgba(0,0,0,0.5);
  backdrop-filter: blur(8px);
  border: none;
  border-radius: 50%;
  color: white;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
}

.course-card:hover .btn-favorite-card {
  opacity: 1;
}

.btn-favorite-card:hover {
  background: rgba(248,113,113,0.8);
  transform: scale(1.1);
}

.btn-favorite-card.favorited {
  opacity: 1;
  background: var(--red);
}

.btn-favorite-card.favorited i {
  animation: heartBeat 0.6s ease;
}

.playlist-scroll {
  flex: 1;
  overflow-y: auto;
  padding: 10px 12px;
  display: flex;
  flex-direction: column;
  gap: 5px;
}

.playlist-scroll::-webkit-scrollbar {
  width: 4px;
}

.playlist-scroll::-webkit-scrollbar-track {
  background: transparent;
}

.playlist-scroll::-webkit-scrollbar-thumb {
  background: var(--border-bright);
  border-radius: 2px;
}

.playlist-scroll::-webkit-scrollbar-thumb:hover {
  background: var(--blue);
}

.playlist-item {
  padding: 10px 12px;
  background: rgba(255,255,255,0.02);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition);
  border: 1px solid transparent;
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

.playlist-item:hover {
  background: var(--bg-hover);
  border-color: var(--border-blue);
}

.playlist-item.active {
  background: rgba(79,142,247,0.12);
  border-color: rgba(79,142,247,0.35);
}

.playlist-item .index {
  width: 26px;
  height: 26px;
  background: var(--bg-secondary);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.78rem;
  font-weight: 600;
  flex-shrink: 0;
  color: var(--text-muted);
}

.playlist-item.active .index {
  background: var(--grad-brand);
  color: white;
  box-shadow: 0 2px 8px rgba(79,142,247,0.4);
}

.playlist-item.completed .index {
  background: linear-gradient(135deg, var(--green) 0%, var(--cyan) 100%);
  color: white;
  box-shadow: 0 2px 8px rgba(52,211,153,0.3);
}

.playlist-item .name {
  flex: 1;
  font-size: 0.85rem;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  color: var(--text-secondary);
  line-height: 1.4;
}

.playlist-item.active .name {
  color: var(--text-primary);
  font-weight: 500;
}

.playlist-item .duration {
  font-size: 0.75rem;
  color: var(--text-dim);
  flex-shrink: 0;
  background: rgba(255,255,255,0.04);
  padding: 2px 6px;
  border-radius: 4px;
}



/* ============================================
   收藏页面
   ============================================ */
.favorites-content {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 32px 80px;
}

.favorite-item {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 16px;
  transition: var(--transition);
  display: flex;
  align-items: center;
  gap: 16px;
}

.favorite-item:hover {
  border-color: var(--border-blue);
  transform: translateX(4px);
}

.favorite-icon {
  width: 60px;
  height: 60px;
  background: linear-gradient(135deg, var(--red) 0%, #ff6b6b 100%);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 1.5rem;
  flex-shrink: 0;
}

.favorite-info {
  flex: 1;
  min-width: 0;
}

.favorite-info h4 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 6px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.favorite-info h4 i {
  color: var(--blue);
  font-size: 0.85rem;
}

.favorite-info p {
  color: var(--text-muted);
  font-size: 0.85rem;
}

.favorite-actions {
  display: flex;
  gap: 8px;
  flex-shrink: 0;
}

.btn-play-fav,
.btn-del-fav {
  padding: 8px 16px;
  border-radius: 20px;
  cursor: pointer;
  transition: var(--transition);
  font-size: 0.82rem;
  display: flex;
  align-items: center;
  gap: 6px;
  border: 1px solid var(--border);
  background: rgba(255,255,255,0.04);
  color: var(--text-secondary);
}

.btn-play-fav:hover {
  background: rgba(79,142,247,0.15);
  border-color: var(--blue);
  color: var(--blue);
}

.btn-del-fav:hover {
  background: rgba(248,113,113,0.15);
  border-color: var(--red);
  color: var(--red);
}

.empty-state {
  text-align: center;
  padding: 80px 20px;
  color: var(--text-muted);
}

.empty-state i {
  font-size: 4rem;
  margin-bottom: 20px;
  opacity: 0.3;
}

.empty-state h3 {
  font-size: 1.2rem;
  margin-bottom: 10px;
  color: var(--text-secondary);
}

.empty-state p {
  font-size: 0.9rem;
  margin-bottom: 24px;
}

/* ============================================
   UI/UX 增强 - 动画 & 交互
   ============================================ */

/* 页面切换增强 */
.page {
  animation: pageSlideIn 0.4s cubic-bezier(0.4,0,0.2,1);
}

@keyframes pageSlideIn {
  from { 
    opacity: 0; 
    transform: translateY(20px); 
  }
  to { 
    opacity: 1; 
    transform: translateY(0); 
  }
}

/* 卡片悬浮效果增强 */
.course-card,
.stat-card,
.progress-course-card,
.chapter-item,
.favorite-item {
  transition: transform 0.3s cubic-bezier(0.4,0,0.2,1), 
              box-shadow 0.3s ease,
              border-color 0.3s ease;
}

/* 按钮点击涟漪效果 */
.btn-primary,
.btn-secondary,
.btn-login,
.btn-checkin {
  position: relative;
  overflow: hidden;
}

.btn-primary::after,
.btn-checkin::after {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  background: rgba(255,255,255,0.3);
  border-radius: 50%;
  transform: translate(-50%, -50%);
  transition: width 0.6s ease, height 0.6s ease;
}

.btn-primary:active::after,
.btn-checkin:active::after {
  width: 300px;
  height: 300px;
}

/* 加载骨架屏 */
.skeleton {
  background: linear-gradient(
    90deg,
    var(--bg-card) 25%,
    var(--bg-card-2) 50%,
    var(--bg-card) 75%
  );
  background-size: 200% 100%;
  animation: skeleton-loading 1.5s ease infinite;
  border-radius: var(--radius-sm);
}

@keyframes skeleton-loading {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

.skeleton-text {
  height: 1em;
  margin-bottom: 0.5em;
}

.skeleton-title {
  height: 1.5em;
  width: 60%;
  margin-bottom: 1em;
}

.skeleton-avatar {
  width: 48px;
  height: 48px;
  border-radius: 50%;
}

/* 滚动条美化 */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: var(--bg-secondary);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb {
  background: var(--border-bright);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--blue);
}

/* 文字选中颜色 */
::selection {
  background: rgba(79,142,247,0.3);
  color: var(--text-primary);
}

/* 焦点样式（无障碍） */
:focus-visible {
  outline: 2px solid var(--blue);
  outline-offset: 2px;
}

/* 卡片悬浮光效 */
.course-card::after {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: var(--radius-lg);
  opacity: 0;
  transition: opacity 0.3s ease;
  background: radial-gradient(
    circle at var(--mouse-x, 50%) var(--mouse-y, 50%),
    rgba(79,142,247,0.15) 0%,
    transparent 50%
  );
  pointer-events: none;
}

.course-card:hover::after {
  opacity: 1;
}

/* 平滑图片加载 */
img {
  opacity: 1;
  transition: opacity 0.3s ease;
}

img.loading {
  opacity: 0;
}

/* 打字机效果 */
.typewriter {
  overflow: hidden;
  white-space: nowrap;
  animation: typewriter 3s steps(40) 1s forwards;
}

@keyframes typewriter {
  from { width: 0; }
  to { width: 100%; }
}

/* 脉冲动画 */
.pulse {
  animation: pulse-animation 2s ease infinite;
}

@keyframes pulse-animation {
  0% { box-shadow: 0 0 0 0 rgba(79,142,247,0.4); }
  70% { box-shadow: 0 0 0 10px rgba(79,142,247,0); }
  100% { box-shadow: 0 0 0 0 rgba(79,142,247,0); }
}

/* 漂浮动画 */
.float {
  animation: float-animation 3s ease-in-out infinite;
}

@keyframes float-animation {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-10px); }
}

/* 渐变文字动画 */
.gradient-text {
  background: linear-gradient(
    90deg,
    var(--blue) 0%,
    var(--purple) 50%,
    var(--blue) 100%
  );
  background-size: 200% auto;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  animation: gradient-flow 3s linear infinite;
}

@keyframes gradient-flow {
  0% { background-position: 0% center; }
  100% { background-position: 200% center; }
}

/* 按钮加载状态 */
.btn-loading {
  pointer-events: none;
  opacity: 0.7;
}

.btn-loading::before {
  content: '';
  display: inline-block;
  width: 14px;
  height: 14px;
  border: 2px solid rgba(255,255,255,0.3);
  border-top-color: white;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin-right: 8px;
  vertical-align: middle;
}

/* 成功/错误动画 */
.success-animation {
  animation: success-pop 0.5s cubic-bezier(0.34,1.56,0.64,1);
}

@keyframes success-pop {
  0% { transform: scale(0.5); opacity: 0; }
  50% { transform: scale(1.1); }
  100% { transform: scale(1); opacity: 1; }
}

.error-shake {
  animation: shake 0.5s cubic-bezier(0.36,0.07,0.19,0.97) both;
}

@keyframes shake {
  10%, 90% { transform: translateX(-1px); }
  20%, 80% { transform: translateX(2px); }
  30%, 50%, 70% { transform: translateX(-4px); }
  40%, 60% { transform: translateX(4px); }
}

/* ============================================
   学习进度页
   ============================================ */
.progress-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  max-width: 900px;
  margin: 0 auto 40px;
  padding: 0 32px;
}

.stat-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 28px 20px;
  text-align: center;
  border: 1px solid var(--border);
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.stat-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 2px;
  background: var(--grad-brand);
  opacity: 0;
  transition: var(--transition);
}

.stat-card:hover {
  border-color: var(--border-blue);
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.stat-card:hover::before {
  opacity: 1;
}

.stat-card i {
  font-size: 2rem;
  margin-bottom: 14px;
  background: var(--grad-brand);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.stat-card .number {
  font-size: 2.2rem;
  font-weight: 900;
  color: var(--text-primary);
  margin-bottom: 6px;
  letter-spacing: -0.03em;
}

.stat-card .label {
  color: var(--text-muted);
  font-size: 0.85rem;
}

.progress-courses {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 32px 80px;
}

.progress-course-card {
  background: var(--bg-card);
  border-radius: var(--radius-lg);
  padding: 28px;
  margin-bottom: 20px;
  border: 1px solid var(--border);
  transition: var(--transition);
}

.progress-course-card:hover {
  border-color: var(--border-blue);
}

.progress-course-header {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 24px;
}

.progress-course-header .icon {
  font-size: 2.2rem;
}

.progress-course-header h4 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.progress-course-header p {
  color: var(--text-muted);
  font-size: 0.85rem;
}

.progress-chapters {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 14px;
}

.progress-chapter {
  background: var(--bg-secondary);
  padding: 16px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
}

.progress-chapter h5 {
  font-size: 0.85rem;
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  gap: 7px;
  color: var(--text-secondary);
}

.progress-chapter h5 i {
  color: var(--blue);
}

.progress-bar-container {
  background: rgba(255,255,255,0.05);
  height: 6px;
  border-radius: 3px;
  overflow: hidden;
  margin-bottom: 8px;
}

.progress-bar-fill {
  height: 100%;
  background: var(--grad-brand);
  border-radius: 3px;
  transition: width 0.8s cubic-bezier(0.4,0,0.2,1);
}

.progress-text {
  font-size: 0.78rem;
  color: var(--text-muted);
  text-align: right;
}

/* ============================================
   登录弹窗 — 高端玻璃态
   ============================================ */
.modal {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.75);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 2000;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  padding: 16px;
}

.modal.active {
  display: flex;
}

.modal-content {
  background: linear-gradient(145deg, #1a2340 0%, #141b2d 100%);
  border-radius: var(--radius-xl);
  width: 100%;
  max-width: 420px;
  padding: 40px;
  position: relative;
  border: 1px solid rgba(255,255,255,0.1);
  animation: modalIn 0.3s cubic-bezier(0.34,1.56,0.64,1);
  box-shadow: 0 30px 80px rgba(0,0,0,0.7), 0 0 0 1px rgba(79,142,247,0.1);
}

.modal-content::before {
  content: '';
  position: absolute;
  top: 0; left: 20%; right: 20%;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(79,142,247,0.5), rgba(167,139,250,0.5), transparent);
}

@keyframes modalIn {
  from { opacity: 0; transform: scale(0.92) translateY(20px); }
  to   { opacity: 1; transform: scale(1) translateY(0); }
}

.modal-close {
  position: absolute;
  top: 14px; right: 14px;
  background: rgba(255,255,255,0.06);
  border: 1px solid var(--border);
  color: var(--text-muted);
  cursor: pointer;
  font-size: 1rem;
  transition: var(--transition);
  width: 32px; height: 32px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
}

.modal-close:hover {
  color: var(--text-primary);
  background: rgba(255,255,255,0.1);
  border-color: var(--border-bright);
}

.modal-header {
  text-align: center;
  margin-bottom: 32px;
}

.modal-header h3 {
  font-size: 1.5rem;
  font-weight: 800;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  letter-spacing: -0.02em;
}

.modal-header h3 i {
  background: var(--grad-brand);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.form-group {
  margin-bottom: 18px;
}

.form-group label {
  display: flex;
  align-items: center;
  gap: 7px;
  margin-bottom: 8px;
  color: var(--text-secondary);
  font-size: 0.85rem;
  font-weight: 500;
}

.form-group label i {
  color: var(--blue);
  font-size: 0.85rem;
}

.form-group input {
  width: 100%;
  padding: 13px 16px;
  background: rgba(255,255,255,0.04);
  border: 1px solid var(--border-bright);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-size: 0.95rem;
  transition: var(--transition);
  -webkit-appearance: none;
}

.form-group input:focus {
  outline: none;
  border-color: var(--blue);
  background: rgba(79,142,247,0.06);
  box-shadow: 0 0 0 3px rgba(79,142,247,0.15);
}

.form-group input::placeholder {
  color: var(--text-dim);
}

.form-actions {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-top: 24px;
}

.form-actions .btn-primary,
.form-actions .btn-secondary {
  width: 100%;
  padding: 14px;
  border-radius: 50px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  justify-content: center;
}

.btn-secondary {
  background: rgba(255,255,255,0.04);
  border: 1px solid var(--border-bright);
  color: var(--text-secondary);
}

.btn-secondary:hover {
  border-color: var(--blue);
  color: var(--text-primary);
  background: rgba(79,142,247,0.08);
}

.form-hint {
  text-align: center;
  font-size: 0.8rem;
  color: var(--text-dim);
  margin-top: 16px;
}

/* ============================================
   Toast 提示
   ============================================ */
.toast {
  position: fixed;
  top: 80px;
  left: 50%;
  transform: translateX(-50%) translateY(-20px);
  background: linear-gradient(145deg, #1a2340 0%, #141b2d 100%);
  padding: 14px 24px;
  border-radius: 50px;
  display: flex;
  align-items: center;
  gap: 10px;
  border: 1px solid var(--border-bright);
  box-shadow: var(--shadow-lg);
  opacity: 0;
  transition: transform 0.35s cubic-bezier(0.34,1.56,0.64,1), opacity 0.3s ease;
  z-index: 9999;
  pointer-events: none;
  font-size: 0.9rem;
  white-space: nowrap;
  max-width: calc(100vw - 32px);
}

.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

.toast.success i { color: var(--green); }
.toast.error   i { color: var(--red); }
.toast.warning i { color: var(--orange); }
.toast.info    i { color: var(--blue); }

/* ============================================
   登录提示横幅
   ============================================ */
.login-notice {
  max-width: 1200px;
  margin: 0 auto 24px;
  padding: 14px 20px;
  background: linear-gradient(135deg, rgba(79,142,247,0.08) 0%, rgba(167,139,250,0.08) 100%);
  border: 1px solid rgba(79,142,247,0.2);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  gap: 12px;
}

.login-notice.inline-notice {
  margin: 0 32px 20px;
  max-width: none;
}

.login-notice i {
  color: var(--blue);
  font-size: 1rem;
  flex-shrink: 0;
}

.login-notice p {
  color: var(--text-secondary);
  font-size: 0.88rem;
  line-height: 1.5;
}

.login-notice a {
  color: var(--blue-light);
  text-decoration: none;
  font-weight: 600;
  transition: var(--transition);
}

.login-notice a:hover {
  color: var(--purple);
  text-decoration: underline;
}

/* ============================================
   预览横幅
   ============================================ */
.preview-banner {
  background: linear-gradient(135deg, rgba(251,191,36,0.08) 0%, rgba(248,113,113,0.08) 100%);
  border: 1px solid rgba(251,191,36,0.2);
  border-radius: var(--radius-sm);
  padding: 11px 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin: 0;
  flex-shrink: 0;
}

.preview-banner-left {
  display: flex;
  align-items: center;
  gap: 8px;
  min-width: 0;
}

.preview-banner i {
  color: var(--orange);
  font-size: 0.95rem;
  flex-shrink: 0;
}

.preview-banner p {
  color: var(--text-secondary);
  font-size: 0.82rem;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.preview-banner .btn-primary {
  padding: 7px 14px;
  font-size: 0.82rem;
  flex-shrink: 0;
  border-radius: 20px;
}

/* ============================================
   未登录 / 空状态
   ============================================ */
.not-logged-in {
  text-align: center;
  padding: 100px 20px;
  color: var(--text-muted);
}

.not-logged-in i {
  font-size: 3.5rem;
  margin-bottom: 20px;
  opacity: 0.3;
  background: var(--grad-brand);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.not-logged-in h3 {
  font-size: 1.2rem;
  font-weight: 600;
  margin-bottom: 10px;
  color: var(--text-secondary);
}

/* ============================================
   加载中
   ============================================ */
.loading {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  padding: 60px;
  color: var(--text-muted);
  font-size: 0.9rem;
}

.loading i {
  font-size: 1.5rem;
  color: var(--blue);
  animation: spin 1s linear infinite;
}

@keyframes spin {
  from { transform: rotate(0deg); }
  to   { transform: rotate(360deg); }
}

/* ============================================
   平板端适配 (1024px - 768px)
   ============================================ */
@media (max-width: 1024px) {
  .hero-title { font-size: 3rem; }
  .header-content { padding: 0 20px; }

  .video-right { width: 300px; }

  .courses-grid {
    grid-template-columns: 1fr;
  }

  .courses-preview {
    padding: 48px 20px 60px;
  }
}

/* ============================================
   手机端 (≤768px)
   ============================================ */
.mobile-nav { display: none; }

@media (max-width: 768px) {

  /* === 顶部导航 === */
  .header { height: 56px; }

  .header-content {
    padding: 0 14px;
    gap: 10px;
  }

  .logo {
    font-size: 1rem;
    gap: 7px;
  }

  .logo i { font-size: 1.25rem; }

  .nav { display: none; }
  .admin-link { display: none !important; }

  .btn-login {
    padding: 7px 14px;
    font-size: 0.82rem;
    gap: 5px;
  }

  .user-info {
    padding: 4px 10px 4px 6px;
    gap: 6px;
  }

  .user-info .avatar {
    width: 28px; height: 28px;
    font-size: 0.78rem;
  }

  .user-info span:not(.avatar) { display: none; }

  .btn-logout {
    padding: 5px 10px;
    font-size: 0.78rem;
  }

  /* === 主内容 === */
  .main-content {
    padding-top: 56px;
    padding-bottom: 64px;
  }

  /* === Hero === */
  .hero {
    min-height: 360px;
    padding: 40px 16px;
  }

  .hero-bg::before { width: 300px; height: 300px; }
  .hero-bg::after  { width: 250px; height: 250px; }

  .hero-badge { font-size: 0.72rem; padding: 5px 12px; margin-bottom: 18px; }

  .hero-title {
    font-size: 2.1rem;
    margin-bottom: 14px;
  }

  .hero-subtitle {
    font-size: 0.88rem;
    margin-bottom: 24px;
  }

  .hero-stats {
    margin-bottom: 28px;
    padding: 16px 0;
    max-width: 280px;
  }

  .stat-number { font-size: 1.7rem; }
  .stat-label  { font-size: 0.75rem; }

  .btn-primary {
    padding: 12px 28px;
    font-size: 0.92rem;
  }

  /* === 课程预览 === */
  .courses-preview {
    padding: 28px 14px 32px;
  }

  .section-title {
    font-size: 1.2rem;
    margin-bottom: 18px;
  }

  .courses-grid {
    grid-template-columns: 1fr;
    gap: 14px;
  }

  .course-card-header {
    padding: 22px 20px 18px;
    min-height: 130px;
  }

  .course-icon { font-size: 2.2rem; margin-bottom: 10px; }

  .course-card-header h3 { font-size: 1.1rem; }

  .course-card-body {
    padding: 16px 20px 20px;
  }

  /* === 页面头部 === */
  .page-header {
    padding: 18px 14px 12px;
    gap: 10px;
  }

  .page-header h2 { font-size: 1.15rem; }

  /* === 课程详情 === */
  .course-content {
    padding: 0 14px 80px;
  }

  .login-notice.inline-notice {
    margin: 0 14px 14px;
  }

  .chapter-header {
    padding: 14px 16px;
  }

  .chapter-header h4 { font-size: 0.92rem; }

  .chapter-lessons { padding: 0 10px 12px; }

  .lesson-item {
    padding: 11px 12px;
    gap: 10px;
  }

  .lesson-item:hover { transform: none; }

  .lesson-item .lesson-icon {
    width: 32px; height: 32px;
    font-size: 0.75rem;
  }

  .lesson-info h5 { font-size: 0.85rem; }

  /* === 视频播放页 - 手机上下布局（视频固定，目录滚动） === */
  .video-page-wrapper {
    flex-direction: column;
    height: calc(100vh - 56px); /* 整页不超出屏幕 */
    overflow: hidden;           /* 禁止整体页面滚动 */
  }

  .video-left {
    flex: none;
    width: 100%;
    overflow: hidden;
    /* 视频区高度 = 屏幕宽度 × 9/16 + 头部 + 进度条 */
    /* 用 flex-shrink:0 保证不被目录区压缩 */
    flex-shrink: 0;
  }

  .video-main {
    height: auto;
    flex-shrink: 0;
  }

  .video-wrapper {
    height: 0;
    padding-bottom: 56.25%; /* 16:9 */
    position: relative;
    flex: none;
  }

  .video-wrapper video {
    position: absolute;
    top: 0; left: 0;
    width: 100%; height: 100%;
  }

  .video-placeholder {
    position: absolute;
  }

  /* 目录区：占满剩余高度，内部滚动，留出底部导航 */
  .video-right {
    flex: 1;                     /* 占满剩余空间 */
    min-height: 0;               /* flex子项必须，否则不会压缩 */
    width: 100%;
    border-left: none;
    border-top: 1px solid var(--border);
    background: var(--bg-card);
    display: flex;
    flex-direction: column;
    overflow: hidden;
  }

  .playlist-scroll {
    flex: 1;
    min-height: 0;
    overflow-y: auto;            /* 只有目录列表内部滚动 */
    -webkit-overflow-scrolling: touch; /* iOS 惯性滚动 */
    padding: 8px 10px 72px;     /* 底部预留底导航高度 */
    gap: 4px;
  }

  .video-header {
    padding: 10px 14px;
    gap: 10px;
  }

  .video-title-info h3 {
    font-size: 0.88rem;
  }

  .video-title-info p { font-size: 0.75rem; }

  .btn-back {
    padding: 7px 12px;
    font-size: 0.8rem;
  }

  .playlist-header {
    padding: 12px 14px;
  }

  .playlist-item {
    padding: 9px 10px;
    gap: 8px;
  }

  .playlist-item .index {
    width: 24px; height: 24px;
    font-size: 0.72rem;
  }

  .playlist-item .name { font-size: 0.82rem; }

  .playlist-item .duration { font-size: 0.72rem; }

  .video-progress-container {
    padding: 8px 14px;
  }

  /* 预览横幅手机端 */
  .preview-banner {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
    padding: 10px 14px;
    margin: 0;
  }

  .preview-banner .btn-primary {
    width: 100%;
    justify-content: center;
    padding: 9px 14px;
  }

  /* === 学习进度 === */
  .progress-stats {
    gap: 10px;
    padding: 0 14px;
    margin-bottom: 20px;
  }

  .stat-card {
    padding: 16px 10px;
  }

  .stat-card i { font-size: 1.5rem; margin-bottom: 10px; }
  .stat-card .number { font-size: 1.7rem; }
  .stat-card .label  { font-size: 0.75rem; }

  .progress-courses {
    padding: 0 14px 80px;
  }

  .progress-course-card {
    padding: 18px;
  }

  .progress-chapters {
    grid-template-columns: 1fr;
    gap: 10px;
  }

  /* === 登录弹窗 === */
  .modal-content {
    padding: 28px 20px;
    max-width: none;
    border-radius: var(--radius-lg);
  }

  /* === Toast === */
  .toast {
    max-width: calc(100vw - 32px);
    font-size: 0.85rem;
    padding: 12px 18px;
    border-radius: 50px;
  }
}

/* ============================================
   手机底部导航
   ============================================ */
@media (max-width: 768px) {
  .mobile-nav {
    display: flex;
    position: fixed;
    bottom: 0; left: 0; right: 0;
    height: 64px;
    background: rgba(6, 8, 16, 0.95);
    backdrop-filter: blur(20px) saturate(180%);
    -webkit-backdrop-filter: blur(20px) saturate(180%);
    border-top: 1px solid var(--border);
    z-index: 999;
    align-items: stretch;
  }

  .mobile-nav::before {
    content: '';
    position: absolute;
    top: 0; left: 10%; right: 10%;
    height: 1px;
    background: linear-gradient(90deg, transparent, rgba(79,142,247,0.4), rgba(167,139,250,0.4), transparent);
  }

  .mobile-nav-item {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 3px;
    color: var(--text-dim);
    cursor: pointer;
    background: none;
    border: none;
    transition: var(--transition);
    padding: 6px 0;
    position: relative;
  }

  .mobile-nav-item i { font-size: 1.1rem; }

  .mobile-nav-item span { font-size: 0.65rem; font-weight: 500; }

  .mobile-nav-item.active {
    color: var(--blue);
  }

  .mobile-nav-item.active::before {
    content: '';
    position: absolute;
    top: 0; left: 25%; right: 25%;
    height: 2px;
    background: var(--grad-brand);
    border-radius: 0 0 2px 2px;
  }

  .mobile-nav-item.active i {
    transform: translateY(-1px);
    filter: drop-shadow(0 0 6px rgba(79,142,247,0.6));
  }
}