/* ========================================
   视频点播网站 - 主样式文件
   红黄色调设计
   ======================================== */

/* CSS 变量定义 */
:root {
  /* 主题色 */
  --primary-red: #E53935;
  --primary-yellow: #FF9800;
  --gradient-main: linear-gradient(135deg, #E53935 0%, #FF9800 100%);
  
  /* 背景色 */
  --bg-light: #FFF8F0;
  --bg-card: #FFFFFF;
  --bg-dark: #2D2D2D;
  
  /* 文字颜色 */
  --text-primary: #333333;
  --text-secondary: #666666;
  --text-muted: #999999;
  --text-light: #FFFFFF;
  
  /* 间距 */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  
  /* 圆角 */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  
  /* 阴影 */
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.12);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.16);
  
  /* 过渡 */
  --transition-fast: 0.2s ease;
  --transition-normal: 0.3s ease;
}

/* 重置样式 */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  background-color: var(--bg-light);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
}

a {
  text-decoration: none;
  color: inherit;
}

ul, ol {
  list-style: none;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

button {
  cursor: pointer;
  border: none;
  background: none;
  font-family: inherit;
}

input {
  font-family: inherit;
  border: none;
  outline: none;
}

/* ========================================
   导航栏样式
   ======================================== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 64px;
  background: var(--gradient-main);
  box-shadow: var(--shadow-md);
  z-index: 1000;
  display: flex;
  align-items: center;
  padding: 0 var(--spacing-md);
}

.navbar-container {
  max-width: 1200px;
  width: 100%;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.navbar-logo {
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
}

.navbar-logo img {
  height: 36px;
  width: auto;
}

.navbar-logo span {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-light);
}

.navbar-menu {
  display: flex;
  align-items: center;
  gap: var(--spacing-lg);
}

.navbar-menu a {
  color: var(--text-light);
  font-size: 1rem;
  font-weight: 500;
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--radius-sm);
  transition: background-color var(--transition-fast);
}

.navbar-menu a:hover,
.navbar-menu a.active {
  background-color: rgba(255, 255, 255, 0.2);
}

.navbar-search {
  display: flex;
  align-items: center;
  background: rgba(255, 255, 255, 0.2);
  border-radius: var(--radius-lg);
  padding: 0 var(--spacing-sm);
  height: 36px;
}

.navbar-search input {
  background: transparent;
  color: var(--text-light);
  width: 180px;
  font-size: 0.875rem;
}

.navbar-search input::placeholder {
  color: rgba(255, 255, 255, 0.7);
}

.navbar-search button {
  color: var(--text-light);
  font-size: 1rem;
}

/* 移动端菜单按钮 */
.navbar-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: var(--spacing-xs);
}

.navbar-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background-color: var(--text-light);
  transition: var(--transition-fast);
}

/* ========================================
   Banner 幻灯片样式
   ======================================== */
.banner {
  margin-top: 64px;
  position: relative;
  width: 100%;
  height: 400px;
  overflow: hidden;
}

.banner-slides {
  position: relative;
  width: 100%;
  height: 100%;
}

.banner-slide {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0;
  transition: opacity var(--transition-normal);
}

.banner-slide.active {
  opacity: 1;
}

.banner-slide img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.banner-content {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  padding: var(--spacing-lg);
  background: linear-gradient(transparent, rgba(0, 0, 0, 0.7));
  color: var(--text-light);
}

.banner-content h2 {
  font-size: 1.75rem;
  font-weight: 600;
  margin-bottom: var(--spacing-xs);
}

.banner-content p {
  font-size: 1rem;
  opacity: 0.9;
}

.banner-dots {
  position: absolute;
  bottom: 100px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: var(--spacing-xs);
}

.banner-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background-color: rgba(255, 255, 255, 0.5);
  cursor: pointer;
  transition: var(--transition-fast);
}

.banner-dot.active {
  background-color: var(--primary-yellow);
  transform: scale(1.2);
}

.banner-nav {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 48px;
  height: 48px;
  background-color: rgba(255, 255, 255, 0.3);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-light);
  font-size: 1.5rem;
  cursor: pointer;
  transition: var(--transition-fast);
}

.banner-nav:hover {
  background-color: rgba(255, 255, 255, 0.5);
}

.banner-nav.prev {
  left: var(--spacing-md);
}

.banner-nav.next {
  right: var(--spacing-md);
}

/* ========================================
   课程列表样式
   ======================================== */
.course-section {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--spacing-xl) var(--spacing-md);
}

.section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--spacing-lg);
}

.section-title {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--text-primary);
  position: relative;
  padding-left: var(--spacing-sm);
}

.section-title::before {
  content: '';
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 4px;
  height: 24px;
  background: var(--gradient-main);
  border-radius: var(--radius-sm);
}

.section-more {
  color: var(--primary-red);
  font-size: 0.875rem;
  display: flex;
  align-items: center;
  gap: 4px;
}

.section-more:hover {
  text-decoration: underline;
}

.course-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--spacing-md);
}

.course-card {
  background: var(--bg-card);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
}

.course-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.course-card-image {
  position: relative;
  width: 100%;
  padding-top: 56.25%;
  overflow: hidden;
}

.course-card-image img {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition-normal);
}

.course-card:hover .course-card-image img {
  transform: scale(1.05);
}

.course-card-badge {
  position: absolute;
  top: var(--spacing-xs);
  left: var(--spacing-xs);
  background: var(--primary-yellow);
  color: var(--text-light);
  font-size: 0.75rem;
  font-weight: 500;
  padding: 2px 8px;
  border-radius: var(--radius-sm);
}

.course-card-duration {
  position: absolute;
  bottom: var(--spacing-xs);
  right: var(--spacing-xs);
  background: rgba(0, 0, 0, 0.7);
  color: var(--text-light);
  font-size: 0.75rem;
  padding: 2px 6px;
  border-radius: var(--radius-sm);
}

.course-card-content {
  padding: var(--spacing-sm);
}

.course-card-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--spacing-xs);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  line-height: 1.4;
}

.course-card-meta {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  color: var(--text-muted);
  font-size: 0.875rem;
}

.course-card-meta span {
  display: flex;
  align-items: center;
  gap: 4px;
}

/* ========================================
   视频播放页样式
   ======================================== */
.player-page {
  margin-top: 64px;
  min-height: calc(100vh - 64px);
}

.player-container {
  max-width: 1000px;
  margin: 0 auto;
  padding: var(--spacing-lg) var(--spacing-md);
}

.player-wrapper {
  position: relative;
  width: 100%;
  background: #000;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
}

.player-wrapper video {
  width: 100%;
  display: block;
}

.video-info {
  padding: var(--spacing-lg) 0;
}

.video-title {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--spacing-sm);
}

.video-meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-md);
  color: var(--text-secondary);
  font-size: 0.875rem;
  margin-bottom: var(--spacing-md);
}

.video-meta-item {
  display: flex;
  align-items: center;
  gap: 4px;
}

.video-description {
  color: var(--text-secondary);
  font-size: 0.9375rem;
  line-height: 1.8;
  padding: var(--spacing-md);
  background: var(--bg-card);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
}

.video-description h3 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--spacing-xs);
}

.video-actions {
  display: flex;
  gap: var(--spacing-sm);
  margin-top: var(--spacing-md);
}

.action-btn {
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
  padding: var(--spacing-xs) var(--spacing-sm);
  background: var(--bg-card);
  border: 1px solid #E0E0E0;
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  font-size: 0.875rem;
  transition: var(--transition-fast);
}

.action-btn:hover {
  border-color: var(--primary-red);
  color: var(--primary-red);
}

/* 推荐课程 */
.recommended-section {
  margin-top: var(--spacing-xl);
}

/* ========================================
   版权栏样式
   ======================================== */
.footer {
  background: var(--bg-dark);
  color: var(--text-light);
  padding: var(--spacing-xl) var(--spacing-md);
  margin-top: var(--spacing-xl);
}

.footer-container {
  max-width: 1200px;
  margin: 0 auto;
  text-align: center;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: var(--spacing-lg);
  margin-bottom: var(--spacing-md);
}

.footer-links a {
  color: rgba(255, 255, 255, 0.7);
  font-size: 0.875rem;
  transition: color var(--transition-fast);
}

.footer-links a:hover {
  color: var(--primary-yellow);
}

.footer-copyright {
  color: rgba(255, 255, 255, 0.5);
  font-size: 0.875rem;
}

/* ========================================
   响应式设计
   ======================================== */

/* 平板设备 (768px - 1023px) */
@media (max-width: 1023px) {
  .course-grid {
    grid-template-columns: repeat(3, 1fr);
  }
  
  .navbar-search input {
    width: 140px;
  }
}

/* 移动端 (< 768px) */
@media (max-width: 767px) {
  .navbar {
    padding: 0 var(--spacing-sm);
  }
  
  .navbar-menu {
    position: fixed;
    top: 64px;
    left: 0;
    right: 0;
    background: var(--gradient-main);
    flex-direction: column;
    padding: var(--spacing-md);
    gap: var(--spacing-sm);
    display: none;
    box-shadow: var(--shadow-md);
  }
  
  .navbar-menu.active {
    display: flex;
  }
  
  .navbar-menu a {
    width: 100%;
    text-align: center;
    padding: var(--spacing-sm);
  }
  
  .navbar-search {
    display: none;
  }
  
  .navbar-toggle {
    display: flex;
  }
  
  .banner {
    height: 200px;
  }
  
  .banner-content h2 {
    font-size: 1.25rem;
  }
  
  .banner-content p {
    font-size: 0.875rem;
  }
  
  .banner-nav {
    width: 36px;
    height: 36px;
    font-size: 1.25rem;
  }
  
  .banner-dots {
    bottom: 60px;
  }
  
  .course-grid {
    grid-template-columns: 1fr;
    gap: var(--spacing-sm);
  }
  
  .course-card-content {
    padding: var(--spacing-xs);
  }
  
  .section-header {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--spacing-xs);
  }
  
  .player-container {
    padding: var(--spacing-sm);
  }
  
  .video-title {
    font-size: 1.25rem;
  }
  
  .video-meta {
    flex-direction: column;
    gap: var(--spacing-xs);
  }
  
  .video-actions {
    flex-wrap: wrap;
  }
  
  .footer-links {
    flex-direction: column;
    gap: var(--spacing-sm);
  }
}

/* ========================================
   工具类
   ======================================== */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

.text-center {
  text-align: center;
}

.mt-1 { margin-top: var(--spacing-xs); }
.mt-2 { margin-top: var(--spacing-sm); }
.mt-3 { margin-top: var(--spacing-md); }
.mt-4 { margin-top: var(--spacing-lg); }

.mb-1 { margin-bottom: var(--spacing-xs); }
.mb-2 { margin-bottom: var(--spacing-sm); }
.mb-3 { margin-bottom: var(--spacing-md); }
.mb-4 { margin-bottom: var(--spacing-lg); }

.hidden { display: none; }

/* 加载动画 */
.loading {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 200px;
}

.loading::after {
  content: '';
  width: 40px;
  height: 40px;
  border: 3px solid var(--bg-light);
  border-top-color: var(--primary-red);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

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

/* 空状态 */
.empty-state {
  text-align: center;
  padding: var(--spacing-xl);
  color: var(--text-muted);
}

.empty-state-icon {
  font-size: 3rem;
  margin-bottom: var(--spacing-sm);
}

.empty-state-text {
  font-size: 1rem;
}