/* ===== 课程详情页布局 ===== */

/* 课程分类分组 */
.course-category {
  margin-bottom: 32px;
}
.category-title {
  font-size: 1.5rem;
  color: #4a5fc9;
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 2px solid #e0e4ff;
}
.category-courses {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
}
.chapter-badge {
  position: absolute;
  top: 8px;
  left: 8px;
  background: rgba(74, 95, 201, 0.85);
  color: #fff;
  font-size: 0.75rem;
  padding: 2px 8px;
  border-radius: 6px;
  z-index: 2;
}
.course-card .course-thumb {
  position: relative;
}

/* ===== 每日一学 · 7大品牌分类标签 ===== */
.category-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 16px;
  margin-bottom: 28px;
  padding: 8px 0;
}
.cat-tab {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 22px;
  border: 2px solid #e2e8f0;
  border-radius: 12px;
  background: #fff;
  color: #4a5568;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.25s ease;
  letter-spacing: 0.3px;
  position: relative;
  user-select: none;
}
.cat-tab .tab-icon {
  font-size: 1.15rem;
  line-height: 1;
}
.cat-tab .tab-label {
  white-space: nowrap;
}
.cat-tab .tab-sub {
  display: none;
  font-size: 0.7rem;
  font-weight: 400;
  opacity: 0.7;
  margin-left: 2px;
}
/* Hover: 各品牌品牌色边框 + 微升效果 */
.cat-tab:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 14px rgba(0,0,0,0.08);
}
.cat-tab[data-cat="all"]:hover {
  border-color: #667eea;
  color: #667eea;
}
.cat-tab[data-cat="Anthropic Academy"]:hover {
  border-color: #DA7C4A;
  color: #DA7C4A;
}
.cat-tab[data-cat="Google AI"]:hover {
  border-color: #4285F4;
  color: #4285F4;
}
.cat-tab[data-cat="Microsoft Learn"]:hover {
  border-color: #00A4EF;
  color: #00A4EF;
}
.cat-tab[data-cat="AWS AI"]:hover {
  border-color: #FF9900;
  color: #FF9900;
}
.cat-tab[data-cat="NVIDIA DLI"]:hover {
  border-color: #76B900;
  color: #76B900;
}
.cat-tab[data-cat="Meta AI"]:hover {
  border-color: #1877F2;
  color: #1877F2;
}
.cat-tab[data-cat="OpenAI Academy"]:hover {
  border-color: #10A37F;
  color: #10A37F;
}
/* Active: 各品牌品牌色实心填充 */
.cat-tab[data-cat="all"].active {
  background: linear-gradient(135deg, #667eea, #764ba2);
  color: #fff;
  border-color: transparent;
  box-shadow: 0 4px 14px rgba(102,126,234,0.35);
}
.cat-tab[data-cat="Anthropic Academy"].active {
  background: #DA7C4A;
  color: #fff;
  border-color: transparent;
  box-shadow: 0 4px 14px rgba(218,124,74,0.35);
}
.cat-tab[data-cat="Google AI"].active {
  background: #4285F4;
  color: #fff;
  border-color: transparent;
  box-shadow: 0 4px 14px rgba(66,133,244,0.35);
}
.cat-tab[data-cat="Microsoft Learn"].active {
  background: #00A4EF;
  color: #fff;
  border-color: transparent;
  box-shadow: 0 4px 14px rgba(0,164,239,0.35);
}
.cat-tab[data-cat="AWS AI"].active {
  background: #FF9900;
  color: #fff;
  border-color: transparent;
  box-shadow: 0 4px 14px rgba(255,153,0,0.35);
}
.cat-tab[data-cat="NVIDIA DLI"].active {
  background: #76B900;
  color: #fff;
  border-color: transparent;
  box-shadow: 0 4px 14px rgba(118,185,0,0.35);
}
.cat-tab[data-cat="Meta AI"].active {
  background: #1877F2;
  color: #fff;
  border-color: transparent;
  box-shadow: 0 4px 14px rgba(24,119,242,0.35);
}
.cat-tab[data-cat="OpenAI Academy"].active {
  background: #10A37F;
  color: #fff;
  border-color: transparent;
  box-shadow: 0 4px 14px rgba(16,163,127,0.35);
}

.course-top-bar {
  margin-bottom: 16px;
}

.back-link {
  color: #4a5fc9;
  text-decoration: none;
  font-size: 0.95rem;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-weight: 500;
}
.back-link:hover {
  text-decoration: underline;
}

.course-header {
  margin-bottom: 28px;
}

.course-header h2 {
  font-size: 1.8rem;
  color: #333;
  margin-bottom: 6px;
}

.course-subtitle {
  color: #777;
  font-size: 1rem;
}

/* ===== 核心：视频在上，教案在下（全宽阅读排版） ===== */
.course-layout {
  display: flex;
  flex-direction: column;
  gap: 28px;
}

/* 视频区 — 全宽 */
.course-video-section {
  width: 100%;
}

.course-video-wrapper {
  width: 100%;
  aspect-ratio: 16 / 9;
  background: #000;
  border-radius: 14px;
  overflow: hidden;
}

.course-video-wrapper video {
  width: 100%;
  height: 100%;
  display: block;
  object-fit: contain;
}

.course-video-wrapper iframe {
  width: 100%;
  height: 100%;
  border: none;
  display: block;
}

/* 教案区 — 全宽，类似阅读文章样式 */
.course-plan-section {
  width: 100%;
  max-width: 100%;
  overflow-y: visible;
  background: #fff;
  border: 1px solid #e8ecf1;
  border-radius: 14px;
  padding: 32px 40px;
  line-height: 1.9;
  box-shadow: 0 2px 12px rgba(0,0,0,0.04);
}
.course-plan-section::-webkit-scrollbar {
  width: 5px;
}
.course-plan-section::-webkit-scrollbar-thumb {
  background: #bbb;
  border-radius: 3px;
}
.course-plan-section h4 {
  color: #667eea;
  font-size: 1.15rem;
  margin-bottom: 20px;
  padding-bottom: 14px;
  border-bottom: 2px solid #e0e4ff;
  letter-spacing: 0.5px;
}

.course-plan-content {
  white-space: pre-wrap;
  font-size: 1rem;
  color: #333;
  max-width: 820px;
  margin: 0 auto;
}
.course-plan-content p {
  margin: 0 0 16px;
}
.course-plan-content h3 {
  font-size: 1.35rem;
  color: #222;
  margin: 28px 0 12px;
  font-weight: 700;
}
.course-plan-content h4 {
  font-size: 1.2rem;
  color: #333;
  margin: 24px 0 10px;
  font-weight: 600;
}
.course-plan-content h5 {
  font-size: 1.08rem;
  color: #444;
  margin: 20px 0 8px;
  font-weight: 600;
}
.course-plan-content h6 {
  font-size: 1rem;
  color: #555;
  margin: 16px 0 6px;
  font-weight: 600;
}
.course-plan-content strong {
  color: #222;
}
.course-plan-content hr {
  margin: 24px 0;
  border: none;
  border-top: 1px solid #e8ecf1;
}
.course-plan-content code {
  background: #f0f2f5;
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 0.88rem;
  color: #d63384;
}
.course-plan-content pre {
  background: #1e1e2e;
  color: #cdd6f4;
  padding: 16px 20px;
  border-radius: 10px;
  overflow-x: auto;
  font-size: 0.88rem;
  line-height: 1.6;
  margin: 16px 0;
}
.course-plan-content pre code {
  background: none;
  color: inherit;
  padding: 0;
  font-size: inherit;
}
.course-plan-content a {
  color: #667eea;
  text-decoration: underline;
}
.course-plan-content a:hover {
  color: #764ba2;
}

/* ===== 评论区 ===== */
.course-comments {
  margin-top: 30px;
}
.course-comments .comment-section {
  border-top: 1px solid #eee;
  padding-top: 24px;
}

/* ===== 响应式 < 900px ===== */
@media (max-width: 900px) {
  .course-layout {
    flex-direction: column;
  }
  .course-video-section {
    flex: none;
    width: 100%;
  }
  .course-video-wrapper {
    aspect-ratio: 16 / 9;
  }
  .course-plan-section {
    flex: none;
    width: 100%;
    min-width: 0;
    max-height: none;
    padding: 24px 20px;
  }
  .course-header h2 {
    font-size: 1.4rem;
  }
  .course-plan-content {
    max-width: 100%;
  }
}