/* ============================================================
   91 修车改装 - 官方网站样式表
   品牌色：#FF6B00 (橙) / #1A1A2E (深夜蓝) / #E8E8E8 (银灰)
   版本：v1.0 | ugnn7z.cn
   ============================================================ */

/* ---- 全局重置 ---- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: 'PingFang SC', 'Microsoft YaHei', 'Hiragino Sans GB', sans-serif;
  background: #0d0d1a;
  color: #e0e0e0;
  line-height: 1.7;
  overflow-x: hidden;
}
a { color: #FF6B00; text-decoration: none; transition: color .25s; }
a:hover { color: #ffaa55; }
img { max-width: 100%; height: auto; display: block; }
ul, ol { list-style: none; }
button { cursor: pointer; border: none; outline: none; }

/* ---- CSS变量 ---- */
:root {
  --orange: #FF6B00;
  --orange-light: #FF9A3C;
  --dark: #0d0d1a;
  --dark2: #1a1a2e;
  --dark3: #16213e;
  --silver: #c8c8d0;
  --white: #f5f5f5;
  --border: rgba(255,107,0,0.2);
  --shadow: 0 8px 32px rgba(0,0,0,0.5);
  --radius: 12px;
  --transition: all .3s ease;
}

/* ---- 滚动条 ---- */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--dark2); }
::-webkit-scrollbar-thumb { background: var(--orange); border-radius: 3px; }

/* ============================================================
   顶部广告横幅
   ============================================================ */
.yziosg { background: linear-gradient(90deg,#FF6B00,#ff9a3c); text-align:center; padding:8px 16px; font-size:.85rem; color:#fff; letter-spacing:.5px; }
.yziosg a { color:#fff; font-weight:700; text-decoration:underline; }

/* ============================================================
   导航栏
   ============================================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 999;
  background: rgba(13,13,26,.96);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}
.nav-inner {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  align-items: center;
  gap: 24px;
  height: 68px;
}
.nav-logo { display: flex; align-items: center; gap: 10px; flex-shrink: 0; }
.nav-logo img.logo-icon { width: 36px; height: 36px; border-radius: 8px; object-fit: cover; }
.nav-logo img.logo-full { height: 40px; width: auto; display: none; }
@media(min-width:768px){ .nav-logo img.logo-full { display: block; } .nav-logo img.logo-icon { display: none; } }
.nav-logo .brand-text { font-size: 1.4rem; font-weight: 900; color: var(--orange); letter-spacing: 1px; }
.nav-menu { display: flex; gap: 4px; flex: 1; }
.nav-menu a {
  color: var(--silver);
  font-size: .9rem;
  padding: 8px 14px;
  border-radius: 8px;
  white-space: nowrap;
  transition: var(--transition);
}
.nav-menu a:hover, .nav-menu a.active { background: var(--orange); color: #fff; }
.nav-actions { display: flex; align-items: center; gap: 12px; margin-left: auto; }
.btn-nav-join {
  background: var(--orange);
  color: #fff;
  padding: 8px 20px;
  border-radius: 20px;
  font-size: .88rem;
  font-weight: 700;
  transition: var(--transition);
}
.btn-nav-join:hover { background: var(--orange-light); color: #fff; transform: translateY(-1px); }
.nav-hamburger { display: none; flex-direction: column; gap: 5px; padding: 8px; }
.nav-hamburger span { display: block; width: 24px; height: 2px; background: var(--silver); border-radius: 2px; transition: var(--transition); }
@media(max-width:900px){
  .nav-menu { display: none; position: absolute; top: 68px; left: 0; right: 0; background: var(--dark2); flex-direction: column; padding: 16px; gap: 4px; border-bottom: 1px solid var(--border); }
  .nav-menu.open { display: flex; }
  .nav-hamburger { display: flex; }
}

/* ============================================================
   搜索框
   ============================================================ */
.search-bar-wrap {
  background: var(--dark3);
  border-bottom: 1px solid var(--border);
  padding: 12px 20px;
}
.search-bar-inner {
  max-width: 1280px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 12px;
}
.search-bar-inner form {
  display: flex;
  flex: 1;
  max-width: 640px;
  background: var(--dark2);
  border: 1px solid var(--border);
  border-radius: 24px;
  overflow: hidden;
}
.search-bar-inner input {
  flex: 1;
  background: transparent;
  border: none;
  padding: 10px 18px;
  color: var(--white);
  font-size: .9rem;
  outline: none;
}
.search-bar-inner input::placeholder { color: #666; }
.search-bar-inner button {
  background: var(--orange);
  color: #fff;
  padding: 10px 20px;
  font-size: .9rem;
  font-weight: 700;
  transition: var(--transition);
}
.search-bar-inner button:hover { background: var(--orange-light); }
.search-hot-tags { display: flex; gap: 8px; flex-wrap: wrap; }
.search-hot-tags span { font-size: .8rem; color: #888; }
.search-hot-tags a {
  font-size: .8rem;
  background: rgba(255,107,0,.12);
  color: var(--orange);
  padding: 3px 10px;
  border-radius: 12px;
  transition: var(--transition);
}
.search-hot-tags a:hover { background: var(--orange); color: #fff; }

/* ============================================================
   面包屑
   ============================================================ */
.breadcrumb {
  max-width: 1280px;
  margin: 0 auto;
  padding: 10px 20px;
  font-size: .82rem;
  color: #888;
  display: flex;
  gap: 6px;
  align-items: center;
}
.breadcrumb a { color: #888; }
.breadcrumb a:hover { color: var(--orange); }
.breadcrumb .sep { color: #555; }
.breadcrumb .current { color: var(--orange); }

/* ============================================================
   Hero Banner 区域
   ============================================================ */
.hero-section {
  position: relative;
  min-height: 560px;
  display: flex;
  align-items: center;
  overflow: hidden;
}
.hero-bg {
  position: absolute;
  inset: 0;
  background-image: url('../images/hero-banner.jpg');
  background-size: cover;
  background-position: center;
  filter: brightness(.45);
  z-index: 0;
}
.hero-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(13,13,26,.85) 0%, rgba(255,107,0,.08) 100%);
  z-index: 1;
}
.hero-content {
  position: relative;
  z-index: 2;
  max-width: 1280px;
  margin: 0 auto;
  padding: 80px 20px;
  width: 100%;
}
.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(255,107,0,.15);
  border: 1px solid var(--orange);
  color: var(--orange);
  padding: 4px 14px;
  border-radius: 20px;
  font-size: .82rem;
  font-weight: 700;
  margin-bottom: 16px;
  letter-spacing: 1px;
}
.hero-title {
  font-size: clamp(2.2rem, 5vw, 3.8rem);
  font-weight: 900;
  line-height: 1.15;
  color: var(--white);
  margin-bottom: 16px;
}
.hero-title .brand-hl { color: var(--orange); }
.hero-desc {
  font-size: 1.05rem;
  color: var(--silver);
  max-width: 560px;
  margin-bottom: 32px;
  line-height: 1.8;
}
.hero-btns { display: flex; gap: 14px; flex-wrap: wrap; }
.btn-primary {
  background: var(--orange);
  color: #fff;
  padding: 14px 32px;
  border-radius: 28px;
  font-size: 1rem;
  font-weight: 700;
  transition: var(--transition);
  display: inline-flex;
  align-items: center;
  gap: 8px;
}
.btn-primary:hover { background: var(--orange-light); color: #fff; transform: translateY(-2px); box-shadow: 0 8px 24px rgba(255,107,0,.4); }
.btn-outline {
  background: transparent;
  color: var(--white);
  padding: 14px 32px;
  border-radius: 28px;
  border: 2px solid rgba(255,255,255,.3);
  font-size: 1rem;
  font-weight: 600;
  transition: var(--transition);
  display: inline-flex;
  align-items: center;
  gap: 8px;
}
.btn-outline:hover { border-color: var(--orange); color: var(--orange); }
.hero-stats {
  display: flex;
  gap: 32px;
  margin-top: 40px;
  flex-wrap: wrap;
}
.hero-stat { text-align: center; }
.hero-stat .num { font-size: 1.8rem; font-weight: 900; color: var(--orange); }
.hero-stat .label { font-size: .78rem; color: #888; margin-top: 2px; }

/* ============================================================
   通用区块样式
   ============================================================ */
.section { padding: 72px 20px; }
.section-inner { max-width: 1280px; margin: 0 auto; }
.section-header { text-align: center; margin-bottom: 48px; }
.section-tag {
  display: inline-block;
  background: rgba(255,107,0,.12);
  color: var(--orange);
  font-size: .78rem;
  font-weight: 700;
  letter-spacing: 2px;
  padding: 4px 14px;
  border-radius: 20px;
  margin-bottom: 12px;
  text-transform: uppercase;
}
.section-title {
  font-size: clamp(1.6rem, 3vw, 2.4rem);
  font-weight: 900;
  color: var(--white);
  line-height: 1.25;
  margin-bottom: 12px;
}
.section-title .hl { color: var(--orange); }
.section-desc { font-size: .95rem; color: #888; max-width: 560px; margin: 0 auto; }

/* ---- 分隔线 ---- */
.divider { height: 1px; background: linear-gradient(90deg, transparent, var(--border), transparent); margin: 0 20px; }

/* ============================================================
   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(--dark2);
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
  transition: var(--transition);
  cursor: pointer;
}
.video-card:hover { transform: translateY(-6px); border-color: var(--orange); box-shadow: 0 16px 40px rgba(255,107,0,.2); }
.video-thumb {
  position: relative;
  aspect-ratio: 16/9;
  overflow: hidden;
  background: #111;
}
.video-thumb img { width: 100%; height: 100%; object-fit: cover; transition: transform .4s; }
.video-card:hover .video-thumb img { transform: scale(1.06); }
.video-play-btn {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(0,0,0,.4);
  opacity: 0;
  transition: opacity .3s;
}
.video-card:hover .video-play-btn { opacity: 1; }
.video-play-btn svg { width: 56px; height: 56px; fill: #fff; filter: drop-shadow(0 4px 12px rgba(0,0,0,.6)); }
.video-duration {
  position: absolute;
  bottom: 8px;
  right: 8px;
  background: rgba(0,0,0,.75);
  color: #fff;
  font-size: .72rem;
  padding: 2px 7px;
  border-radius: 4px;
}
.video-tag {
  position: absolute;
  top: 8px;
  left: 8px;
  background: var(--orange);
  color: #fff;
  font-size: .7rem;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 4px;
}
.video-info { padding: 14px 16px; }
.video-info h3 { font-size: .92rem; font-weight: 700; color: var(--white); margin-bottom: 8px; line-height: 1.4; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
.video-meta { display: flex; gap: 12px; font-size: .78rem; color: #888; }
.video-meta span { display: flex; align-items: center; gap: 4px; }

/* ============================================================
   服务功能卡片
   ============================================================ */
.service-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 24px; }
.service-card {
  background: var(--dark2);
  border-radius: var(--radius);
  padding: 32px 24px;
  border: 1px solid var(--border);
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}
.service-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--orange), var(--orange-light));
  transform: scaleX(0);
  transition: transform .3s;
}
.service-card:hover::before { transform: scaleX(1); }
.service-card:hover { transform: translateY(-4px); border-color: var(--orange); }
.service-icon { font-size: 2.4rem; margin-bottom: 16px; }
.service-card h3 { font-size: 1.1rem; font-weight: 800; color: var(--white); margin-bottom: 10px; }
.service-card p { font-size: .88rem; color: #888; line-height: 1.7; }
.service-card .service-link { display: inline-block; margin-top: 16px; color: var(--orange); font-size: .85rem; font-weight: 700; }
.service-card .service-link:hover { color: var(--orange-light); }

/* ============================================================
   专家展示
   ============================================================ */
.expert-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 28px; }
.expert-card {
  background: var(--dark2);
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
  transition: var(--transition);
  text-align: center;
}
.expert-card:hover { transform: translateY(-6px); border-color: var(--orange); }
.expert-avatar { position: relative; }
.expert-avatar img { width: 100%; aspect-ratio: 1; object-fit: cover; }
.expert-badge {
  position: absolute;
  bottom: 10px;
  right: 10px;
  background: var(--orange);
  color: #fff;
  font-size: .7rem;
  font-weight: 700;
  padding: 3px 8px;
  border-radius: 4px;
}
.expert-info { padding: 20px 16px; }
.expert-info h3 { font-size: 1.05rem; font-weight: 800; color: var(--white); margin-bottom: 4px; }
.expert-role { font-size: .82rem; color: var(--orange); margin-bottom: 10px; }
.expert-desc { font-size: .82rem; color: #888; line-height: 1.6; margin-bottom: 14px; }
.expert-awards { display: flex; flex-wrap: wrap; gap: 6px; justify-content: center; margin-bottom: 14px; }
.expert-awards span { font-size: .72rem; background: rgba(255,107,0,.1); color: var(--orange); padding: 2px 8px; border-radius: 10px; }
.expert-btns { display: flex; gap: 8px; justify-content: center; }
.expert-btns a { font-size: .8rem; padding: 6px 14px; border-radius: 16px; font-weight: 700; transition: var(--transition); }
.btn-contact { background: var(--orange); color: #fff; }
.btn-contact:hover { background: var(--orange-light); color: #fff; }
.btn-works { background: transparent; border: 1px solid var(--border); color: var(--silver); }
.btn-works:hover { border-color: var(--orange); color: var(--orange); }

/* ============================================================
   合作品牌Logo墙
   ============================================================ */
.partner-wall {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  justify-content: center;
  align-items: center;
}
.partner-logo {
  background: var(--dark2);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px 24px;
  font-size: .9rem;
  font-weight: 700;
  color: #888;
  transition: var(--transition);
  min-width: 120px;
  text-align: center;
}
.partner-logo:hover { border-color: var(--orange); color: var(--orange); }

/* ============================================================
   FAQ 手风琴
   ============================================================ */
.faq-list { max-width: 800px; margin: 0 auto; display: flex; flex-direction: column; gap: 12px; }
.faq-item {
  background: var(--dark2);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  overflow: hidden;
  transition: border-color .3s;
}
.faq-item.open { border-color: var(--orange); }
.faq-q {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 22px;
  cursor: pointer;
  font-weight: 700;
  color: var(--white);
  font-size: .95rem;
  gap: 12px;
}
.faq-q .faq-icon { flex-shrink: 0; width: 22px; height: 22px; background: rgba(255,107,0,.15); border-radius: 50%; display: flex; align-items: center; justify-content: center; color: var(--orange); font-size: 1rem; transition: transform .3s; }
.faq-item.open .faq-q .faq-icon { transform: rotate(45deg); }
.faq-a { display: none; padding: 0 22px 18px; font-size: .88rem; color: #888; line-height: 1.8; }
.faq-item.open .faq-a { display: block; }

/* ============================================================
   用户评价
   ============================================================ */
.review-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 24px; }
.review-card {
  background: var(--dark2);
  border-radius: var(--radius);
  padding: 24px;
  border: 1px solid var(--border);
  transition: var(--transition);
}
.review-card:hover { border-color: var(--orange); transform: translateY(-4px); }
.review-header { display: flex; align-items: center; gap: 12px; margin-bottom: 14px; }
.review-avatar { width: 44px; height: 44px; border-radius: 50%; background: linear-gradient(135deg, var(--orange), #ff9a3c); display: flex; align-items: center; justify-content: center; font-size: 1.1rem; font-weight: 900; color: #fff; flex-shrink: 0; }
.review-user h4 { font-size: .9rem; font-weight: 700; color: var(--white); }
.review-user .review-date { font-size: .75rem; color: #666; }
.review-stars { color: #FFD700; font-size: .9rem; margin-bottom: 10px; }
.review-text { font-size: .88rem; color: #aaa; line-height: 1.7; }
.review-tags { display: flex; gap: 6px; flex-wrap: wrap; margin-top: 12px; }
.review-tags span { font-size: .72rem; background: rgba(255,107,0,.1); color: var(--orange); padding: 2px 8px; border-radius: 10px; }

/* ============================================================
   社区功能模块
   ============================================================ */
.community-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 20px; }
.community-card {
  background: var(--dark2);
  border-radius: var(--radius);
  padding: 28px 20px;
  text-align: center;
  border: 1px solid var(--border);
  transition: var(--transition);
}
.community-card:hover { border-color: var(--orange); transform: translateY(-4px); }
.community-icon { font-size: 2.8rem; margin-bottom: 14px; }
.community-card h3 { font-size: 1rem; font-weight: 800; color: var(--white); margin-bottom: 8px; }
.community-card p { font-size: .82rem; color: #888; line-height: 1.6; }
.community-num { font-size: 1.4rem; font-weight: 900; color: var(--orange); margin-top: 10px; }

/* ============================================================
   联系我们
   ============================================================ */
.contact-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 24px; }
.contact-card {
  background: var(--dark2);
  border-radius: var(--radius);
  padding: 28px 24px;
  border: 1px solid var(--border);
  transition: var(--transition);
}
.contact-card:hover { border-color: var(--orange); }
.contact-card h3 { font-size: 1.05rem; font-weight: 800; color: var(--white); margin-bottom: 16px; padding-bottom: 12px; border-bottom: 1px solid var(--border); }
.contact-item { display: flex; gap: 10px; align-items: flex-start; margin-bottom: 12px; font-size: .88rem; color: #aaa; }
.contact-item .ci-label { color: var(--orange); font-weight: 700; flex-shrink: 0; min-width: 56px; }

/* ============================================================
   AI赋能区块
   ============================================================ */
.ai-section { background: linear-gradient(135deg, var(--dark2) 0%, #0d1b2a 100%); }
.ai-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 24px; }
.ai-card {
  background: rgba(255,107,0,.05);
  border: 1px solid rgba(255,107,0,.2);
  border-radius: var(--radius);
  padding: 28px 22px;
  transition: var(--transition);
}
.ai-card:hover { background: rgba(255,107,0,.1); border-color: var(--orange); transform: translateY(-4px); }
.ai-card .ai-num { font-size: 2.4rem; font-weight: 900; color: rgba(255,107,0,.2); line-height: 1; margin-bottom: 12px; }
.ai-card h3 { font-size: 1rem; font-weight: 800; color: var(--white); margin-bottom: 8px; }
.ai-card p { font-size: .85rem; color: #888; line-height: 1.7; }

/* ============================================================
   How-To 加入社区
   ============================================================ */
.howto-steps { display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); gap: 20px; counter-reset: step; }
.howto-step {
  background: var(--dark2);
  border-radius: var(--radius);
  padding: 28px 20px;
  border: 1px solid var(--border);
  text-align: center;
  position: relative;
  transition: var(--transition);
}
.howto-step:hover { border-color: var(--orange); }
.howto-step::before {
  counter-increment: step;
  content: counter(step);
  position: absolute;
  top: -14px;
  left: 50%;
  transform: translateX(-50%);
  width: 28px;
  height: 28px;
  background: var(--orange);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: .8rem;
  font-weight: 900;
  color: #fff;
}
.howto-step h4 { font-size: .95rem; font-weight: 800; color: var(--white); margin-bottom: 8px; margin-top: 8px; }
.howto-step p { font-size: .82rem; color: #888; line-height: 1.6; }

/* ============================================================
   社交分享
   ============================================================ */
.share-bar { display: flex; gap: 12px; flex-wrap: wrap; justify-content: center; }
.share-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  border-radius: 24px;
  font-size: .88rem;
  font-weight: 700;
  transition: var(--transition);
  border: 1px solid var(--border);
  color: var(--silver);
  background: var(--dark2);
}
.share-btn:hover { transform: translateY(-2px); }
.share-btn.wechat:hover { background: #07C160; border-color: #07C160; color: #fff; }
.share-btn.weibo:hover { background: #E6162D; border-color: #E6162D; color: #fff; }
.share-btn.douyin:hover { background: #010101; border-color: #69C9D0; color: #69C9D0; }
.share-btn.bilibili:hover { background: #00A1D6; border-color: #00A1D6; color: #fff; }

/* ============================================================
   页脚
   ============================================================ */
.site-footer {
  background: var(--dark2);
  border-top: 1px solid var(--border);
  padding: 56px 20px 24px;
}
.footer-inner { max-width: 1280px; margin: 0 auto; }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px; margin-bottom: 40px; }
@media(max-width:900px){ .footer-grid { grid-template-columns: 1fr 1fr; } }
@media(max-width:560px){ .footer-grid { grid-template-columns: 1fr; } }
.footer-brand .footer-logo { display: flex; align-items: center; gap: 10px; margin-bottom: 14px; }
.footer-brand .footer-logo img { height: 36px; }
.footer-brand .footer-logo .brand-name { font-size: 1.3rem; font-weight: 900; color: var(--orange); }
.footer-brand p { font-size: .85rem; color: #888; line-height: 1.8; margin-bottom: 16px; }
.footer-col h4 { font-size: .9rem; font-weight: 800; color: var(--white); margin-bottom: 16px; padding-bottom: 8px; border-bottom: 1px solid var(--border); }
.footer-col ul li { margin-bottom: 8px; }
.footer-col ul li a { font-size: .85rem; color: #888; transition: var(--transition); }
.footer-col ul li a:hover { color: var(--orange); padding-left: 4px; }
.footer-qr-row { display: flex; gap: 24px; flex-wrap: wrap; }
.footer-qr { text-align: center; }
.footer-qr img { width: 90px; height: 90px; border-radius: 8px; border: 2px solid var(--border); }
.footer-qr p { font-size: .75rem; color: #888; margin-top: 6px; }
.footer-bottom {
  border-top: 1px solid var(--border);
  padding-top: 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  font-size: .8rem;
  color: #666;
}
.footer-bottom a { color: #666; }
.footer-bottom a:hover { color: var(--orange); }
.footer-update { color: var(--orange); font-size: .78rem; }

/* ============================================================
   回到顶部
   ============================================================ */
.back-to-top {
  position: fixed;
  bottom: 28px;
  right: 24px;
  width: 44px;
  height: 44px;
  background: var(--orange);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  cursor: pointer;
  z-index: 998;
  opacity: 0;
  transform: translateY(20px);
  transition: var(--transition);
  box-shadow: 0 4px 16px rgba(255,107,0,.4);
}
.back-to-top.show { opacity: 1; transform: translateY(0); }
.back-to-top:hover { background: var(--orange-light); transform: translateY(-3px); }

/* ============================================================
   标签云
   ============================================================ */
.tag-cloud { display: flex; flex-wrap: wrap; gap: 8px; }
.tag-cloud a {
  font-size: .8rem;
  background: rgba(255,107,0,.08);
  color: #aaa;
  padding: 4px 12px;
  border-radius: 14px;
  border: 1px solid var(--border);
  transition: var(--transition);
}
.tag-cloud a:hover { background: var(--orange); color: #fff; border-color: var(--orange); }

/* ============================================================
   内页 Hero
   ============================================================ */
.inner-hero {
  background: linear-gradient(135deg, var(--dark2) 0%, #0d1b2a 100%);
  padding: 56px 20px 40px;
  border-bottom: 1px solid var(--border);
}
.inner-hero-inner { max-width: 1280px; margin: 0 auto; }
.inner-hero h1 { font-size: clamp(1.8rem, 3vw, 2.8rem); font-weight: 900; color: var(--white); margin-bottom: 10px; }
.inner-hero h1 .hl { color: var(--orange); }
.inner-hero p { font-size: .95rem; color: #888; max-width: 560px; }

/* ============================================================
   视频播放器内页
   ============================================================ */
.player-wrap {
  background: #000;
  border-radius: var(--radius);
  overflow: hidden;
  aspect-ratio: 16/9;
  width: 100%;
  max-width: 960px;
  margin: 0 auto;
}
.player-wrap video { width: 100%; height: 100%; object-fit: contain; }
.video-detail-grid { display: grid; grid-template-columns: 1fr 320px; gap: 28px; max-width: 1280px; margin: 0 auto; }
@media(max-width:900px){ .video-detail-grid { grid-template-columns: 1fr; } }
.video-detail-info { background: var(--dark2); border-radius: var(--radius); padding: 24px; border: 1px solid var(--border); }
.video-detail-info h2 { font-size: 1.3rem; font-weight: 800; color: var(--white); margin-bottom: 12px; }
.video-actions { display: flex; gap: 12px; flex-wrap: wrap; margin: 16px 0; }
.video-actions button {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 18px;
  border-radius: 20px;
  font-size: .85rem;
  font-weight: 700;
  background: var(--dark3);
  color: var(--silver);
  border: 1px solid var(--border);
  transition: var(--transition);
}
.video-actions button:hover { background: var(--orange); color: #fff; border-color: var(--orange); }
.video-actions button.active { background: var(--orange); color: #fff; border-color: var(--orange); }

/* ============================================================
   404 页面
   ============================================================ */
.error-page { min-height: 60vh; display: flex; align-items: center; justify-content: center; text-align: center; padding: 40px 20px; }
.error-page .err-code { font-size: 8rem; font-weight: 900; color: var(--orange); opacity: .15; line-height: 1; }
.error-page h2 { font-size: 1.6rem; font-weight: 800; color: var(--white); margin: -20px 0 12px; }
.error-page p { color: #888; margin-bottom: 24px; }

/* ============================================================
   响应式
   ============================================================ */
@media(max-width:768px){
  .section { padding: 48px 16px; }
  .hero-section { min-height: 420px; }
  .hero-content { padding: 60px 16px; }
  .video-grid { grid-template-columns: 1fr 1fr; }
  .expert-grid { grid-template-columns: 1fr 1fr; }
}
@media(max-width:480px){
  .video-grid { grid-template-columns: 1fr; }
  .expert-grid { grid-template-columns: 1fr; }
  .hero-btns { flex-direction: column; }
  .hero-stats { gap: 20px; }
}

/* ============================================================
   动画
   ============================================================ */
@keyframes fadeInUp { from { opacity:0; transform:translateY(24px); } to { opacity:1; transform:translateY(0); } }
.fade-in-up { animation: fadeInUp .6s ease both; }
@keyframes pulse { 0%,100%{transform:scale(1);} 50%{transform:scale(1.04);} }
.pulse { animation: pulse 2s infinite; }

/* ============================================================
   懒加载占位
   ============================================================ */
img[loading="lazy"] { background: var(--dark2); }

/* ============================================================
   隐私/条款页
   ============================================================ */
.legal-content { max-width: 800px; margin: 0 auto; padding: 40px 20px; }
.legal-content h2 { font-size: 1.3rem; font-weight: 800; color: var(--white); margin: 28px 0 10px; }
.legal-content p, .legal-content li { font-size: .9rem; color: #aaa; line-height: 1.9; margin-bottom: 10px; }
.legal-content ul { padding-left: 20px; list-style: disc; }