/* ===== 51视频 原创样式表 ===== */
/* 配色：活力红 #e74c3c + 深蓝灰 #2c3e50 + 琥珀金 #f39c12 */

:root {
  --primary: #e74c3c;
  --primary-dark: #c0392b;
  --secondary: #2c3e50;
  --accent: #f39c12;
  --bg: #f5f6fa;
  --card: #ffffff;
  --text: #2c3e50;
  --text-light: #7f8c8d;
  --border: #e0e3e8;
  --shadow: 0 4px 20px rgba(44,62,80,0.08);
  --radius: 12px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  overflow-x: hidden;
}

a { color: var(--primary); text-decoration: none; transition: color .25s; }
a:hover { color: var(--primary-dark); }

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

.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }

/* ===== 顶部导航 ===== */
.site-header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  background: linear-gradient(135deg, var(--secondary), #1a252f);
  box-shadow: 0 2px 16px rgba(0,0,0,0.18);
  transition: background .3s;
}

.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  max-width: 1200px; margin: 0 auto; padding: 0 20px; height: 64px;
}

.logo-link { display: flex; align-items: center; gap: 10px; }
.logo-link img { height: 38px; width: auto; }
.logo-text { color: #fff; font-size: 1.3rem; font-weight: 700; letter-spacing: 1px; }

.main-nav { display: flex; gap: 6px; }
.main-nav a {
  color: rgba(255,255,255,0.85); padding: 8px 16px; border-radius: 8px;
  font-size: 0.95rem; font-weight: 500; transition: all .25s;
}
.main-nav a:hover, .main-nav a.active {
  color: #fff; background: var(--primary);
}

.search-box {
  display: flex; align-items: center; background: rgba(255,255,255,0.12);
  border-radius: 24px; padding: 4px 6px 4px 16px; border: 1px solid rgba(255,255,255,0.15);
}
.search-box input {
  background: none; border: none; outline: none; color: #fff;
  font-size: 0.9rem; width: 140px; padding: 6px 0;
}
.search-box input::placeholder { color: rgba(255,255,255,0.5); }
.search-box button {
  background: var(--primary); border: none; color: #fff; padding: 7px 14px;
  border-radius: 20px; cursor: pointer; font-size: 0.85rem; transition: background .25s;
}
.search-box button:hover { background: var(--primary-dark); }

.mobile-toggle {
  display: none; background: none; border: none; color: #fff;
  font-size: 1.5rem; cursor: pointer;
}

/* ===== Banner区域 ===== */
.hero-banner {
  position: relative; margin-top: 64px; overflow: hidden;
  background: linear-gradient(135deg, var(--secondary), #1a252f);
  min-height: 480px; display: flex; align-items: center;
}

.hero-bg {
  position: absolute; top: 0; left: 0; width: 100%; height: 100%;
  object-fit: cover; opacity: 0.35;
}

.hero-content {
  position: relative; z-index: 2; max-width: 1200px; margin: 0 auto;
  padding: 60px 20px; display: flex; align-items: center; gap: 60px; width: 100%;
}

.hero-text { flex: 1; }
.hero-text h1 { color: #fff; font-size: 2.6rem; line-height: 1.3; margin-bottom: 16px; }
.hero-text h1 span { color: var(--accent); }
.hero-text p { color: rgba(255,255,255,0.85); font-size: 1.1rem; margin-bottom: 28px; line-height: 1.8; }

.hero-btns { display: flex; gap: 16px; flex-wrap: wrap; }
.btn-primary {
  display: inline-flex; align-items: center; gap: 8px;
  background: var(--primary); color: #fff; padding: 14px 32px;
  border-radius: 30px; font-size: 1rem; font-weight: 600;
  transition: all .3s; border: none; cursor: pointer;
}
.btn-primary:hover { background: var(--primary-dark); transform: translateY(-2px); color: #fff; }

.btn-outline {
  display: inline-flex; align-items: center; gap: 8px;
  background: transparent; color: #fff; padding: 14px 32px;
  border-radius: 30px; font-size: 1rem; font-weight: 600;
  border: 2px solid rgba(255,255,255,0.4); transition: all .3s; cursor: pointer;
}
.btn-outline:hover { border-color: var(--accent); color: var(--accent); }

.hero-visual { flex: 0 0 420px; }
.hero-visual img { border-radius: 16px; box-shadow: 0 20px 60px rgba(0,0,0,0.3); }

/* ===== 数据统计条 ===== */
.stats-bar {
  background: var(--card); padding: 30px 0; box-shadow: var(--shadow);
  position: relative; z-index: 3; margin-top: -30px; border-radius: 16px 16px 0 0;
  max-width: 1200px; margin-left: auto; margin-right: auto;
}

.stats-grid {
  display: flex; justify-content: space-around; text-align: center; flex-wrap: wrap;
}

.stat-item { padding: 10px 20px; }
.stat-num { font-size: 2rem; font-weight: 800; color: var(--primary); }
.stat-label { font-size: 0.9rem; color: var(--text-light); margin-top: 4px; }

/* ===== 通用区块 ===== */
.section { padding: 60px 0; }
.section-alt { background: var(--card); }

.section-header { text-align: center; margin-bottom: 44px; }
.section-header h2 {
  font-size: 1.9rem; color: var(--secondary); margin-bottom: 12px;
  position: relative; display: inline-block;
}
.section-header h2::after {
  content: ''; position: absolute; bottom: -8px; left: 50%; transform: translateX(-50%);
  width: 50px; height: 3px; background: var(--primary); border-radius: 2px;
}
.section-header p { color: var(--text-light); font-size: 1rem; margin-top: 16px; }

/* ===== 视频卡片网格 ===== */
.video-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 24px;
}

.video-card {
  background: var(--card); border-radius: var(--radius); overflow: hidden;
  box-shadow: var(--shadow); transition: transform .3s, box-shadow .3s;
}
.video-card:hover { transform: translateY(-6px); box-shadow: 0 12px 36px rgba(44,62,80,0.15); }

.video-thumb {
  position: relative; padding-top: 56.25%; overflow: hidden; background: #1a252f;
}
.video-thumb img {
  position: absolute; top: 0; left: 0; width: 100%; height: 100%; object-fit: cover;
  transition: transform .4s;
}
.video-card:hover .video-thumb img { transform: scale(1.08); }

.play-btn {
  position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%);
  width: 56px; height: 56px; background: rgba(231,76,60,0.9); border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  opacity: 0; transition: opacity .3s, transform .3s;
}
.play-btn::after {
  content: ''; width: 0; height: 0;
  border-left: 18px solid #fff; border-top: 11px solid transparent; border-bottom: 11px solid transparent;
  margin-left: 4px;
}
.video-card:hover .play-btn { opacity: 1; transform: translate(-50%, -50%) scale(1.1); }

.video-duration {
  position: absolute; bottom: 8px; right: 8px; background: rgba(0,0,0,0.75);
  color: #fff; padding: 2px 8px; border-radius: 4px; font-size: 0.8rem;
}

.video-info { padding: 16px; }
.video-info h3 { font-size: 1rem; color: var(--text); margin-bottom: 8px; line-height: 1.5; }
.video-meta { display: flex; gap: 16px; font-size: 0.82rem; color: var(--text-light); }
.video-meta span { display: flex; align-items: center; gap: 4px; }
.video-desc { font-size: 0.88rem; color: var(--text-light); margin-top: 8px; line-height: 1.6; }
.video-tags { display: flex; gap: 6px; flex-wrap: wrap; margin-top: 10px; }
.video-tags span {
  background: #fef0e7; color: var(--accent); padding: 3px 10px;
  border-radius: 12px; font-size: 0.78rem;
}

/* ===== 横向滚动区 ===== */
.scroll-row {
  display: flex; gap: 20px; overflow-x: auto; padding-bottom: 16px;
  scroll-snap-type: x mandatory; -webkit-overflow-scrolling: touch;
}
.scroll-row::-webkit-scrollbar { height: 6px; }
.scroll-row::-webkit-scrollbar-track { background: var(--border); border-radius: 3px; }
.scroll-row::-webkit-scrollbar-thumb { background: var(--primary); border-radius: 3px; }
.scroll-row .video-card { flex: 0 0 300px; scroll-snap-align: start; }

/* ===== 左右交替布局 ===== */
.alternate-block {
  display: flex; align-items: center; gap: 48px; margin-bottom: 48px;
}
.alternate-block:nth-child(even) { flex-direction: row-reverse; }
.alternate-block .block-img { flex: 0 0 48%; border-radius: var(--radius); overflow: hidden; }
.alternate-block .block-img img { border-radius: var(--radius); }
.alternate-block .block-text { flex: 1; }
.alternate-block .block-text h3 { font-size: 1.4rem; color: var(--secondary); margin-bottom: 12px; }
.alternate-block .block-text p { color: var(--text-light); line-height: 1.8; }

/* ===== AI赋能三列 ===== */
.ai-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 28px; }
.ai-card {
  background: var(--card); border-radius: var(--radius); padding: 36px 28px;
  text-align: center; box-shadow: var(--shadow); transition: transform .3s;
  border-top: 3px solid transparent;
}
.ai-card:hover { transform: translateY(-4px); border-top-color: var(--primary); }
.ai-icon {
  width: 64px; height: 64px; margin: 0 auto 20px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  border-radius: 16px; display: flex; align-items: center; justify-content: center;
  font-size: 1.8rem; color: #fff;
}
.ai-card h3 { font-size: 1.15rem; color: var(--secondary); margin-bottom: 10px; }
.ai-card p { font-size: 0.9rem; color: var(--text-light); line-height: 1.7; }

/* ===== 社区六宫格 ===== */
.community-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px;
}
.community-card {
  background: var(--card); border-radius: var(--radius); padding: 28px;
  box-shadow: var(--shadow); transition: all .3s; position: relative; overflow: hidden;
}
.community-card::before {
  content: ''; position: absolute; top: 0; left: 0; width: 4px; height: 100%;
  background: var(--primary); transition: width .3s;
}
.community-card:hover::before { width: 6px; }
.community-card:hover { transform: translateX(4px); }
.community-card h3 { font-size: 1.1rem; color: var(--secondary); margin-bottom: 8px; }
.community-card p { font-size: 0.9rem; color: var(--text-light); line-height: 1.7; }
.community-stats { display: flex; gap: 16px; margin-top: 12px; font-size: 0.82rem; color: var(--accent); }

/* ===== 专家卡片 ===== */
.expert-scroll {
  display: flex; gap: 24px; overflow-x: auto; padding-bottom: 16px;
  scroll-snap-type: x mandatory;
}
.expert-scroll::-webkit-scrollbar { height: 6px; }
.expert-scroll::-webkit-scrollbar-thumb { background: var(--primary); border-radius: 3px; }

.expert-card {
  flex: 0 0 260px; background: var(--card); border-radius: var(--radius);
  padding: 28px; text-align: center; box-shadow: var(--shadow);
  scroll-snap-align: start; transition: transform .3s;
}
.expert-card:hover { transform: translateY(-4px); }
.expert-card img {
  width: 90px; height: 90px; border-radius: 50%; object-fit: cover;
  margin: 0 auto 16px; border: 3px solid var(--primary);
}
.expert-card h4 { font-size: 1.05rem; color: var(--secondary); margin-bottom: 4px; }
.expert-card .role { font-size: 0.85rem; color: var(--primary); margin-bottom: 10px; }
.expert-card p { font-size: 0.85rem; color: var(--text-light); line-height: 1.6; }
.expert-card .expert-btns { display: flex; gap: 8px; justify-content: center; margin-top: 14px; }
.expert-card .expert-btns a {
  padding: 6px 14px; border-radius: 16px; font-size: 0.8rem; font-weight: 500;
}
.expert-card .expert-btns .btn-sm-primary { background: var(--primary); color: #fff; }
.expert-card .expert-btns .btn-sm-outline { border: 1px solid var(--border); color: var(--text-light); }

/* ===== FAQ手风琴 ===== */
.faq-list { max-width: 800px; margin: 0 auto; }
.faq-item {
  background: var(--card); border-radius: var(--radius); margin-bottom: 12px;
  box-shadow: var(--shadow); overflow: hidden;
}
.faq-q {
  padding: 18px 24px; cursor: pointer; display: flex;
  justify-content: space-between; align-items: center;
  font-weight: 600; color: var(--secondary); font-size: 1rem;
  transition: background .25s;
}
.faq-q:hover { background: #fafbfc; }
.faq-q::after { content: '+'; font-size: 1.4rem; color: var(--primary); transition: transform .3s; }
.faq-item.active .faq-q::after { transform: rotate(45deg); }
.faq-a {
  max-height: 0; overflow: hidden; transition: max-height .35s ease;
  padding: 0 24px; color: var(--text-light); line-height: 1.8; font-size: 0.95rem;
}
.faq-item.active .faq-a { max-height: 300px; padding: 0 24px 18px; }

/* ===== 用户评价 ===== */
.review-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr)); gap: 24px; }
.review-card {
  background: var(--card); border-radius: var(--radius); padding: 24px;
  box-shadow: var(--shadow); position: relative;
}
.review-card::before {
  content: '\201C'; position: absolute; top: 12px; left: 18px;
  font-size: 3rem; color: var(--primary); opacity: 0.15; font-family: serif;
}
.review-stars { color: var(--accent); font-size: 0.9rem; margin-bottom: 10px; }
.review-text { font-size: 0.95rem; color: var(--text); line-height: 1.7; margin-bottom: 14px; }
.review-author { display: flex; align-items: center; gap: 10px; }
.review-avatar {
  width: 40px; height: 40px; border-radius: 50%;
  background: var(--primary); color: #fff; display: flex;
  align-items: center; justify-content: center; font-weight: 700; font-size: 0.9rem;
}
.review-name { font-weight: 600; font-size: 0.9rem; color: var(--secondary); }
.review-date { font-size: 0.8rem; color: var(--text-light); }

/* ===== 合作品牌墙 ===== */
.brand-wall {
  display: flex; justify-content: center; gap: 40px; flex-wrap: wrap;
  align-items: center; padding: 20px 0;
}
.brand-wall span {
  font-size: 1.1rem; color: var(--text-light); font-weight: 600;
  padding: 12px 24px; background: var(--card); border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}

/* ===== 社交分享 ===== */
.share-bar { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; padding: 20px 0; }
.share-btn {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 10px 20px; border-radius: 24px; font-size: 0.9rem;
  font-weight: 500; color: #fff; transition: transform .25s;
}
.share-btn:hover { transform: scale(1.05); color: #fff; }
.share-wechat { background: #07c160; }
.share-weibo { background: #e6162d; }
.share-douyin { background: #161823; }
.share-bilibili { background: #00a1d6; }

/* ===== 页脚 ===== */
.site-footer {
  background: var(--secondary); color: rgba(255,255,255,0.75); padding: 50px 0 0;
}

.footer-grid {
  display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px;
  max-width: 1200px; margin: 0 auto; padding: 0 20px 40px;
}

.footer-brand img { height: 36px; margin-bottom: 14px; }
.footer-brand p { font-size: 0.9rem; line-height: 1.7; }

.footer-col h4 {
  color: #fff; font-size: 1rem; margin-bottom: 16px;
  padding-bottom: 8px; border-bottom: 2px solid var(--primary);
  display: inline-block;
}
.footer-col a {
  display: block; color: rgba(255,255,255,0.65); font-size: 0.9rem;
  padding: 4px 0; transition: color .25s;
}
.footer-col a:hover { color: var(--accent); }

.footer-qr { display: flex; gap: 16px; }
.footer-qr img { width: 100px; height: 100px; border-radius: 8px; }

.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.1);
  padding: 18px 20px; text-align: center; font-size: 0.85rem;
  max-width: 1200px; margin: 0 auto;
}

/* ===== 面包屑 ===== */
.breadcrumb {
  padding: 16px 0; font-size: 0.88rem; color: var(--text-light);
  margin-top: 64px;
}
.breadcrumb a { color: var(--primary); }
.breadcrumb span { margin: 0 8px; }

/* ===== 联系信息 ===== */
.contact-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 24px; }
.contact-card {
  background: var(--card); border-radius: var(--radius); padding: 28px;
  box-shadow: var(--shadow); text-align: center;
}
.contact-card h3 { font-size: 1.1rem; color: var(--secondary); margin-bottom: 10px; }
.contact-card p { font-size: 0.9rem; color: var(--text-light); line-height: 1.7; }

/* ===== How-To步骤 ===== */
.howto-steps { max-width: 700px; margin: 0 auto; }
.howto-step {
  display: flex; gap: 20px; margin-bottom: 28px; align-items: flex-start;
}
.step-num {
  flex: 0 0 44px; height: 44px; background: var(--primary); color: #fff;
  border-radius: 50%; display: flex; align-items: center; justify-content: center;
  font-weight: 800; font-size: 1.1rem;
}
.step-content h4 { font-size: 1.05rem; color: var(--secondary); margin-bottom: 4px; }
.step-content p { font-size: 0.9rem; color: var(--text-light); line-height: 1.7; }

/* ===== 内页通用 ===== */
.page-hero {
  margin-top: 64px; padding: 50px 0;
  background: linear-gradient(135deg, var(--secondary), #1a252f);
  color: #fff; text-align: center;
}
.page-hero h1 { font-size: 2rem; margin-bottom: 12px; }
.page-hero p { font-size: 1rem; color: rgba(255,255,255,0.8); }

.page-content { padding: 40px 0 60px; }

/* ===== 响应式 ===== */
@media (max-width: 992px) {
  .main-nav { display: none; }
  .mobile-toggle { display: block; }
  .main-nav.open {
    display: flex; flex-direction: column; position: absolute;
    top: 64px; left: 0; right: 0; background: var(--secondary);
    padding: 16px; gap: 4px;
  }
  .hero-content { flex-direction: column; text-align: center; }
  .hero-visual { flex: 0 0 auto; max-width: 360px; }
  .hero-btns { justify-content: center; }
  .ai-grid { grid-template-columns: 1fr; }
  .community-grid { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .alternate-block, .alternate-block:nth-child(even) { flex-direction: column; }
}

@media (max-width: 640px) {
  .hero-text h1 { font-size: 1.8rem; }
  .section-header h2 { font-size: 1.5rem; }
  .stats-grid { flex-direction: column; gap: 16px; }
  .community-grid { grid-template-columns: 1fr; }
  .video-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
  .search-box { display: none; }
  .review-grid { grid-template-columns: 1fr; }
}

/* ===== 干扰标签隐藏 ===== */
.jammer { position: absolute; width: 0; height: 0; overflow: hidden; opacity: 0; pointer-events: none; }