/* ============================================================
   蜜桃 - 蜜桃与蜜桃社区 | cekdkf.cn
   原创主题样式 v1.0
   ============================================================ */

/* ---- 全局变量 ---- */
:root {
  --primary: #ff6b00;
  --primary-dark: #cc5500;
  --secondary: #1a6bff;
  --secondary-dark: #0050cc;
  --dark: #0d0d1a;
  --dark-2: #141428;
  --dark-3: #1e1e38;
  --dark-4: #252545;
  --light: #f0f2ff;
  --light-2: #d8dcff;
  --text: #c8ccee;
  --text-muted: #7880aa;
  --white: #ffffff;
  --card-bg: #181830;
  --border: #2a2a50;
  --radius: 12px;
  --radius-sm: 6px;
  --shadow: 0 4px 24px rgba(0,0,0,0.4);
  --shadow-hover: 0 8px 40px rgba(255,107,0,0.25);
  --transition: 0.3s ease;
  --font-main: 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
}

/* ---- 重置 ---- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: var(--font-main);
  background: var(--dark);
  color: var(--text);
  line-height: 1.7;
  overflow-x: hidden;
}
a { color: var(--primary); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--primary-dark); }
img { max-width: 100%; height: auto; display: block; }
ul, ol { list-style: none; }
button { cursor: pointer; border: none; outline: none; font-family: var(--font-main); }

/* ---- 干扰标签隐藏 ---- */
.kktu-noise { display: none !important; visibility: hidden !important; }

/* ---- 滚动条 ---- */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--dark-2); }
::-webkit-scrollbar-thumb { background: var(--primary); border-radius: 3px; }

/* ============================================================
   顶部公告栏
   ============================================================ */
.top-bar {
  background: linear-gradient(90deg, var(--primary-dark), var(--secondary-dark));
  color: var(--white);
  text-align: center;
  padding: 8px 20px;
  font-size: 13px;
  letter-spacing: 0.5px;
}
.top-bar a { color: var(--white); font-weight: 600; }

/* ============================================================
   导航栏
   ============================================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: rgba(13,13,26,0.96);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  box-shadow: 0 2px 20px rgba(0,0,0,0.5);
}
.header-inner {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  align-items: center;
  gap: 24px;
  height: 68px;
}
.site-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}
.site-logo img {
  width: 42px;
  height: 42px;
  object-fit: contain;
}
.site-logo .logo-text {
  font-size: 22px;
  font-weight: 800;
  color: var(--white);
  letter-spacing: -0.5px;
}
.site-logo .logo-text span { color: var(--primary); }

.main-nav {
  flex: 1;
  display: flex;
  align-items: center;
  gap: 4px;
}
.main-nav a {
  color: var(--text);
  font-size: 14px;
  font-weight: 500;
  padding: 6px 14px;
  border-radius: var(--radius-sm);
  transition: all var(--transition);
  white-space: nowrap;
}
.main-nav a:hover,
.main-nav a.active {
  color: var(--white);
  background: var(--primary);
}

/* 搜索框 */
.header-search {
  display: flex;
  align-items: center;
  background: var(--dark-3);
  border: 1px solid var(--border);
  border-radius: 24px;
  padding: 6px 14px;
  gap: 8px;
  min-width: 200px;
  transition: border-color var(--transition);
}
.header-search:focus-within { border-color: var(--primary); }
.header-search input {
  background: none;
  border: none;
  outline: none;
  color: var(--text);
  font-size: 14px;
  width: 100%;
  font-family: var(--font-main);
}
.header-search input::placeholder { color: var(--text-muted); }
.header-search button {
  background: none;
  color: var(--text-muted);
  font-size: 16px;
  padding: 0;
  transition: color var(--transition);
}
.header-search button:hover { color: var(--primary); }

/* 汉堡菜单 */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  padding: 4px;
}
.hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--white);
  border-radius: 2px;
  transition: all var(--transition);
}

/* ============================================================
   面包屑
   ============================================================ */
.breadcrumb {
  background: var(--dark-2);
  border-bottom: 1px solid var(--border);
  padding: 10px 0;
}
.breadcrumb-inner {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--text-muted);
}
.breadcrumb-inner a { color: var(--text-muted); }
.breadcrumb-inner a:hover { color: var(--primary); }
.breadcrumb-inner .sep { color: var(--border); }
.breadcrumb-inner .current { color: var(--primary); }

/* ============================================================
   Hero 横幅
   ============================================================ */
.hero-section {
  position: relative;
  min-height: 580px;
  display: flex;
  align-items: center;
  overflow: hidden;
}
.hero-bg {
  position: absolute;
  inset: 0;
  background-size: cover;
  background-position: center;
  filter: brightness(0.45);
  transform: scale(1.05);
  transition: transform 8s ease;
}
.hero-section:hover .hero-bg { transform: scale(1.0); }
.hero-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(13,13,26,0.85) 0%, rgba(255,107,0,0.15) 100%);
}
.hero-content {
  position: relative;
  z-index: 2;
  max-width: 1280px;
  margin: 0 auto;
  padding: 80px 20px;
}
.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(255,107,0,0.2);
  border: 1px solid var(--primary);
  color: var(--primary);
  font-size: 12px;
  font-weight: 600;
  padding: 4px 12px;
  border-radius: 20px;
  margin-bottom: 20px;
  text-transform: uppercase;
  letter-spacing: 1px;
}
.hero-content h1 {
  font-size: clamp(32px, 5vw, 60px);
  font-weight: 900;
  color: var(--white);
  line-height: 1.2;
  margin-bottom: 20px;
}
.hero-content h1 .brand { color: var(--primary); }
.hero-content p {
  font-size: 18px;
  color: var(--light-2);
  max-width: 600px;
  margin-bottom: 36px;
}
.hero-actions { display: flex; gap: 16px; flex-wrap: wrap; }
.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--primary);
  color: var(--white);
  font-size: 15px;
  font-weight: 700;
  padding: 14px 32px;
  border-radius: var(--radius);
  transition: all var(--transition);
  box-shadow: 0 4px 20px rgba(255,107,0,0.4);
}
.btn-primary:hover {
  background: var(--primary-dark);
  color: var(--white);
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(255,107,0,0.5);
}
.btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(255,255,255,0.1);
  border: 1px solid rgba(255,255,255,0.3);
  color: var(--white);
  font-size: 15px;
  font-weight: 600;
  padding: 14px 32px;
  border-radius: var(--radius);
  transition: all var(--transition);
  backdrop-filter: blur(4px);
}
.btn-secondary:hover {
  background: rgba(255,255,255,0.2);
  color: var(--white);
  transform: translateY(-2px);
}
.hero-stats {
  display: flex;
  gap: 40px;
  margin-top: 48px;
  flex-wrap: wrap;
}
.hero-stat { text-align: center; }
.hero-stat .num {
  font-size: 32px;
  font-weight: 900;
  color: var(--primary);
  display: block;
}
.hero-stat .label { font-size: 13px; color: var(--text-muted); }

/* ============================================================
   通用区块
   ============================================================ */
.section {
  padding: 72px 0;
}
.section-alt { background: var(--dark-2); }
.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 20px;
}
.section-header {
  text-align: center;
  margin-bottom: 48px;
}
.section-tag {
  display: inline-block;
  background: rgba(255,107,0,0.15);
  color: var(--primary);
  font-size: 12px;
  font-weight: 700;
  padding: 4px 14px;
  border-radius: 20px;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 12px;
}
.section-title {
  font-size: clamp(24px, 3.5vw, 38px);
  font-weight: 800;
  color: var(--white);
  margin-bottom: 12px;
}
.section-title .accent { color: var(--primary); }
.section-desc {
  font-size: 16px;
  color: var(--text-muted);
  max-width: 560px;
  margin: 0 auto;
}

/* ============================================================
   视频卡片
   ============================================================ */
.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
}
.video-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
  transition: all var(--transition);
  cursor: pointer;
}
.video-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-hover);
  border-color: var(--primary);
}
.video-thumb {
  position: relative;
  aspect-ratio: 16/9;
  overflow: hidden;
  background: var(--dark-3);
}
.video-thumb img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.5s ease;
}
.video-card:hover .video-thumb img { transform: scale(1.08); }
.play-overlay {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(0,0,0,0);
  transition: background var(--transition);
}
.video-card:hover .play-overlay { background: rgba(0,0,0,0.45); }
.play-btn {
  width: 56px;
  height: 56px;
  background: var(--primary);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transform: scale(0.7);
  transition: all var(--transition);
  box-shadow: 0 4px 20px rgba(255,107,0,0.6);
}
.video-card:hover .play-btn {
  opacity: 1;
  transform: scale(1);
}
.play-btn svg { width: 22px; height: 22px; fill: var(--white); margin-left: 3px; }
.video-duration {
  position: absolute;
  bottom: 8px;
  right: 8px;
  background: rgba(0,0,0,0.75);
  color: var(--white);
  font-size: 12px;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: 4px;
}
.video-tag {
  position: absolute;
  top: 8px;
  left: 8px;
  background: var(--primary);
  color: var(--white);
  font-size: 11px;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 4px;
  text-transform: uppercase;
}
.video-info { padding: 16px; }
.video-info h3 {
  font-size: 15px;
  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;
  align-items: center;
  gap: 12px;
  font-size: 12px;
  color: var(--text-muted);
}
.video-meta span { display: flex; align-items: center; gap: 4px; }

/* ============================================================
   功能模块卡片
   ============================================================ */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 20px;
}
.feature-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 24px;
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
}
.feature-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--primary), var(--secondary));
  opacity: 0;
  transition: opacity var(--transition);
}
.feature-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-hover); border-color: var(--primary); }
.feature-card:hover::before { opacity: 1; }
.feature-icon {
  width: 52px;
  height: 52px;
  background: rgba(255,107,0,0.15);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  margin-bottom: 16px;
}
.feature-card h3 { font-size: 16px; font-weight: 700; color: var(--white); margin-bottom: 8px; }
.feature-card p { font-size: 13px; color: var(--text-muted); line-height: 1.6; }

/* ============================================================
   专家展示
   ============================================================ */
.expert-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 24px;
}
.expert-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: all var(--transition);
}
.expert-card:hover { transform: translateY(-6px); box-shadow: var(--shadow-hover); border-color: var(--primary); }
.expert-photo {
  aspect-ratio: 4/3;
  overflow: hidden;
}
.expert-photo img { width: 100%; height: 100%; object-fit: cover; transition: transform 0.5s ease; }
.expert-card:hover .expert-photo img { transform: scale(1.06); }
.expert-info { padding: 20px; }
.expert-name { font-size: 18px; font-weight: 800; color: var(--white); margin-bottom: 4px; }
.expert-title { font-size: 13px; color: var(--primary); font-weight: 600; margin-bottom: 12px; }
.expert-desc { font-size: 13px; color: var(--text-muted); line-height: 1.6; margin-bottom: 16px; }
.expert-tags { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 16px; }
.expert-tag {
  background: rgba(26,107,255,0.15);
  color: var(--secondary);
  font-size: 11px;
  padding: 3px 10px;
  border-radius: 20px;
  border: 1px solid rgba(26,107,255,0.3);
}
.expert-actions { display: flex; gap: 10px; }
.btn-sm {
  flex: 1;
  text-align: center;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  font-size: 13px;
  font-weight: 600;
  transition: all var(--transition);
}
.btn-sm-primary { background: var(--primary); color: var(--white); }
.btn-sm-primary:hover { background: var(--primary-dark); color: var(--white); }
.btn-sm-outline { border: 1px solid var(--border); color: var(--text); }
.btn-sm-outline:hover { border-color: var(--primary); color: var(--primary); }

/* ============================================================
   合作品牌墙
   ============================================================ */
.brand-wall {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 16px;
}
.brand-item {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  text-align: center;
  transition: all var(--transition);
}
.brand-item:hover { border-color: var(--primary); background: var(--dark-3); }
.brand-item .brand-name { font-size: 14px; font-weight: 700; color: var(--white); margin-top: 8px; }
.brand-item .brand-icon { font-size: 32px; }

/* ============================================================
   用户评价
   ============================================================ */
.review-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 20px;
}
.review-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  transition: all var(--transition);
}
.review-card:hover { border-color: var(--primary); transform: translateY(-3px); }
.review-header { display: flex; align-items: center; gap: 14px; margin-bottom: 16px; }
.review-avatar {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  font-weight: 800;
  color: var(--white);
  flex-shrink: 0;
}
.review-user .name { font-size: 15px; font-weight: 700; color: var(--white); }
.review-user .date { font-size: 12px; color: var(--text-muted); }
.review-stars { color: #ffd700; font-size: 14px; margin-bottom: 12px; }
.review-text { font-size: 14px; color: var(--text); line-height: 1.7; }

/* ============================================================
   FAQ
   ============================================================ */
.faq-list { max-width: 800px; margin: 0 auto; }
.faq-item {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 12px;
  overflow: hidden;
}
.faq-question {
  width: 100%;
  background: none;
  color: var(--white);
  font-size: 15px;
  font-weight: 600;
  padding: 18px 20px;
  text-align: left;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  transition: color var(--transition);
  font-family: var(--font-main);
}
.faq-question:hover { color: var(--primary); }
.faq-icon { font-size: 20px; color: var(--primary); transition: transform var(--transition); flex-shrink: 0; }
.faq-item.open .faq-icon { transform: rotate(45deg); }
.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease, padding 0.3s ease;
  padding: 0 20px;
  font-size: 14px;
  color: var(--text-muted);
  line-height: 1.8;
}
.faq-item.open .faq-answer { max-height: 300px; padding: 0 20px 18px; }

/* ============================================================
   联系区块
   ============================================================ */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  align-items: start;
}
.contact-info h2 { font-size: 28px; font-weight: 800; color: var(--white); margin-bottom: 20px; }
.contact-item {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  margin-bottom: 20px;
}
.contact-icon {
  width: 44px;
  height: 44px;
  background: rgba(255,107,0,0.15);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  flex-shrink: 0;
}
.contact-item .label { font-size: 12px; color: var(--text-muted); margin-bottom: 2px; }
.contact-item .value { font-size: 15px; color: var(--white); font-weight: 600; }
.qr-row { display: flex; gap: 24px; margin-top: 28px; }
.qr-box { text-align: center; }
.qr-box img { width: 120px; height: 120px; border-radius: var(--radius-sm); border: 2px solid var(--border); }
.qr-box p { font-size: 12px; color: var(--text-muted); margin-top: 8px; }
.social-links { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 24px; }
.social-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--dark-3);
  border: 1px solid var(--border);
  color: var(--text);
  font-size: 13px;
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  transition: all var(--transition);
}
.social-btn:hover { border-color: var(--primary); color: var(--primary); }

/* ============================================================
   底部
   ============================================================ */
.site-footer {
  background: var(--dark-2);
  border-top: 1px solid var(--border);
  padding: 60px 0 0;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 48px;
}
.footer-brand .logo-wrap { display: flex; align-items: center; gap: 10px; margin-bottom: 16px; }
.footer-brand .logo-wrap img { width: 36px; height: 36px; object-fit: contain; }
.footer-brand .logo-wrap span { font-size: 20px; font-weight: 800; color: var(--white); }
.footer-brand .logo-wrap span em { color: var(--primary); font-style: normal; }
.footer-brand p { font-size: 13px; color: var(--text-muted); line-height: 1.8; max-width: 280px; }
.footer-col h4 { font-size: 14px; font-weight: 700; color: var(--white); margin-bottom: 16px; }
.footer-col ul li { margin-bottom: 10px; }
.footer-col ul li a { font-size: 13px; color: var(--text-muted); transition: color var(--transition); }
.footer-col ul li a:hover { color: var(--primary); }
.footer-bottom {
  border-top: 1px solid var(--border);
  padding: 20px 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  font-size: 13px;
  color: var(--text-muted);
}
.footer-bottom a { color: var(--text-muted); }
.footer-bottom a:hover { color: var(--primary); }
.update-time { color: var(--text-muted); font-size: 12px; }

/* ============================================================
   分享栏
   ============================================================ */
.share-bar {
  background: var(--dark-3);
  border-top: 1px solid var(--border);
  padding: 16px 0;
}
.share-inner {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}
.share-label { font-size: 13px; color: var(--text-muted); font-weight: 600; }
.share-btns { display: flex; gap: 10px; flex-wrap: wrap; }
.share-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  border-radius: var(--radius-sm);
  font-size: 13px;
  font-weight: 600;
  transition: all var(--transition);
  border: 1px solid transparent;
}
.share-wechat { background: rgba(9,187,7,0.15); color: #09bb07; border-color: rgba(9,187,7,0.3); }
.share-weibo { background: rgba(230,22,45,0.15); color: #e6162d; border-color: rgba(230,22,45,0.3); }
.share-douyin { background: rgba(0,0,0,0.3); color: #fff; border-color: rgba(255,255,255,0.2); }
.share-bilibili { background: rgba(0,161,214,0.15); color: #00a1d6; border-color: rgba(0,161,214,0.3); }
.share-btn:hover { transform: translateY(-2px); box-shadow: 0 4px 12px rgba(0,0,0,0.3); }

/* ============================================================
   内页 Banner
   ============================================================ */
.page-banner {
  background: linear-gradient(135deg, var(--dark-3) 0%, var(--dark-2) 100%);
  border-bottom: 1px solid var(--border);
  padding: 60px 0;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.page-banner::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(ellipse at center, rgba(255,107,0,0.08) 0%, transparent 60%);
  pointer-events: none;
}
.page-banner h1 { font-size: 36px; font-weight: 900; color: var(--white); margin-bottom: 12px; }
.page-banner h1 .accent { color: var(--primary); }
.page-banner p { font-size: 16px; color: var(--text-muted); max-width: 560px; margin: 0 auto; }

/* ============================================================
   加入社区指南
   ============================================================ */
.join-steps {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 20px;
  counter-reset: step;
}
.step-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 20px;
  text-align: center;
  position: relative;
  transition: all var(--transition);
}
.step-card:hover { border-color: var(--primary); transform: translateY(-4px); }
.step-num {
  width: 44px;
  height: 44px;
  background: var(--primary);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  font-weight: 900;
  color: var(--white);
  margin: 0 auto 16px;
}
.step-card h3 { font-size: 15px; font-weight: 700; color: var(--white); margin-bottom: 8px; }
.step-card p { font-size: 13px; color: var(--text-muted); }

/* ============================================================
   AI 赋能区块
   ============================================================ */
.ai-section { position: relative; overflow: hidden; }
.ai-bg {
  position: absolute;
  inset: 0;
  background-size: cover;
  background-position: center;
  opacity: 0.12;
}
.ai-content { position: relative; z-index: 2; }
.ai-features {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.ai-card {
  background: rgba(26,26,56,0.8);
  border: 1px solid rgba(26,107,255,0.3);
  border-radius: var(--radius);
  padding: 28px;
  backdrop-filter: blur(8px);
  transition: all var(--transition);
}
.ai-card:hover { border-color: var(--secondary); box-shadow: 0 8px 30px rgba(26,107,255,0.2); transform: translateY(-4px); }
.ai-icon { font-size: 36px; margin-bottom: 16px; }
.ai-card h3 { font-size: 16px; font-weight: 700; color: var(--white); margin-bottom: 10px; }
.ai-card p { font-size: 13px; color: var(--text-muted); line-height: 1.7; }

/* ============================================================
   响应式
   ============================================================ */
@media (max-width: 1024px) {
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .contact-grid { grid-template-columns: 1fr; }
  .ai-features { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 768px) {
  .main-nav { display: none; position: absolute; top: 68px; left: 0; right: 0; background: var(--dark-2); flex-direction: column; padding: 16px; gap: 4px; border-bottom: 1px solid var(--border); z-index: 999; }
  .main-nav.open { display: flex; }
  .main-nav a { padding: 10px 16px; }
  .hamburger { display: flex; }
  .header-search { min-width: 140px; }
  .hero-content { padding: 60px 20px; }
  .hero-stats { gap: 24px; }
  .footer-grid { grid-template-columns: 1fr; }
  .ai-features { grid-template-columns: 1fr; }
  .video-grid { grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); }
  .qr-row { flex-direction: column; align-items: flex-start; }
}
@media (max-width: 480px) {
  .hero-content h1 { font-size: 28px; }
  .section { padding: 48px 0; }
  .section-title { font-size: 22px; }
  .video-grid { grid-template-columns: 1fr; }
  .feature-grid { grid-template-columns: 1fr; }
  .expert-grid { grid-template-columns: 1fr; }
  .review-grid { grid-template-columns: 1fr; }
}

/* ============================================================
   工具类
   ============================================================ */
.text-center { text-align: center; }
.mt-8 { margin-top: 8px; }
.mt-16 { margin-top: 16px; }
.mt-24 { margin-top: 24px; }
.mt-32 { margin-top: 32px; }
.mb-8 { margin-bottom: 8px; }
.mb-16 { margin-bottom: 16px; }
.mb-24 { margin-bottom: 24px; }
.mb-32 { margin-bottom: 32px; }
.flex { display: flex; }
.flex-center { display: flex; align-items: center; justify-content: center; }
.gap-12 { gap: 12px; }
.gap-16 { gap: 16px; }
.hidden { display: none; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0,0,0,0); }

/* 视频播放模态框 */
.video-modal {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 9999;
  background: rgba(0,0,0,0.9);
  align-items: center;
  justify-content: center;
}
.video-modal.active { display: flex; }
.modal-inner {
  position: relative;
  width: 90%;
  max-width: 900px;
  background: var(--dark-2);
  border-radius: var(--radius);
  overflow: hidden;
}
.modal-close {
  position: absolute;
  top: 12px;
  right: 12px;
  width: 36px;
  height: 36px;
  background: rgba(0,0,0,0.6);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--white);
  font-size: 20px;
  z-index: 10;
  cursor: pointer;
  transition: background var(--transition);
}
.modal-close:hover { background: var(--primary); }
.modal-video { width: 100%; aspect-ratio: 16/9; background: #000; display: flex; align-items: center; justify-content: center; }
.modal-video-placeholder { color: var(--text-muted); text-align: center; padding: 40px; }
.modal-video-placeholder .big-icon { font-size: 60px; margin-bottom: 16px; }

/* 加载动画 */
.lazy-img { opacity: 0; transition: opacity 0.5s ease; }
.lazy-img.loaded { opacity: 1; }

/* ============================================================
   关于我们页面 - 响应式
   ============================================================ */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
}
@media (max-width: 768px) {
  .about-grid { grid-template-columns: 1fr; }
  .contact-grid { grid-template-columns: 1fr; }
  .qr-row { flex-direction: row; }
  .page-banner h1 { font-size: 26px; }
  .footer-bottom .container { flex-direction: column; align-items: flex-start; }
}

/* ============================================================
   加入社区 - 步骤卡片
   ============================================================ */
@media (max-width: 600px) {
  .join-steps { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 400px) {
  .join-steps { grid-template-columns: 1fr; }
}

/* ============================================================
   视频卡片 - 标题 h2 兼容
   ============================================================ */
.video-card h2 {
  font-size: 15px;
  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;
}