/* ===== 91 品牌网站 - 原创样式 ===== */
/* 颜色方案：赛车红 #E8350F | 深夜蓝黑 #1A1A2E | 金属金 #F5A623 */

:root {
  --brand-red: #E8350F;
  --brand-dark: #1A1A2E;
  --brand-gold: #F5A623;
  --bg-deep: #0D0D14;
  --text-light: #F0F0F0;
  --card-bg: #1C1C30;
  --card-hover: #262645;
  --border-subtle: rgba(232,53,15,0.25);
  --shadow-glow: 0 4px 30px rgba(232,53,15,0.15);
}

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

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

body {
  font-family: "PingFang SC","Microsoft YaHei","Helvetica Neue",Arial,sans-serif;
  background: var(--bg-deep);
  color: var(--text-light);
  line-height: 1.7;
  overflow-x: hidden;
}

a { color: var(--brand-gold); text-decoration:none; transition: color .3s; }
a:hover { color: var(--brand-red); }

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

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

/* ===== Header ===== */
.site-header {
  position:fixed; top:0; left:0; width:100%; z-index:1000;
  background: rgba(13,13,20,0.95);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-subtle);
  transition: background .3s;
}

.header-inner {
  display:flex; align-items:center; justify-content:space-between;
  max-width:1200px; margin:0 auto; padding:10px 20px;
}

.logo-link { display:flex; align-items:center; gap:10px; }
.logo-link img { height:48px; width:auto; }
.logo-text { font-size:1.5rem; font-weight:800; color:var(--brand-red); letter-spacing:2px; }

.main-nav { display:flex; align-items:center; gap:0; }
.main-nav a {
  padding:10px 16px; color:var(--text-light); font-size:.95rem; font-weight:500;
  position:relative; transition: color .3s;
}
.main-nav a:hover, .main-nav a.active { color:var(--brand-red); }
.main-nav a::after {
  content:''; position:absolute; bottom:0; left:50%; width:0; height:2px;
  background:var(--brand-red); transition:all .3s; transform:translateX(-50%);
}
.main-nav a:hover::after, .main-nav a.active::after { width:60%; }

/* Search Box */
.search-bar {
  max-width:1200px; margin:0 auto; padding:8px 20px;
  background: rgba(28,28,48,0.6);
}
.search-bar form {
  display:flex; max-width:500px; margin:0 auto;
}
.search-bar input {
  flex:1; padding:8px 16px; border:1px solid var(--border-subtle);
  background:var(--card-bg); color:var(--text-light); border-radius:4px 0 0 4px;
  font-size:.9rem; outline:none;
}
.search-bar input:focus { border-color:var(--brand-red); }
.search-bar button {
  padding:8px 20px; background:var(--brand-red); color:#fff; border:none;
  border-radius:0 4px 4px 0; cursor:pointer; font-size:.9rem; transition:background .3s;
}
.search-bar button:hover { background:#c42a0a; }

/* ===== Banner ===== */
.hero-banner {
  position:relative; width:100%; min-height:70vh;
  background-size:cover; background-position:center; background-repeat:no-repeat;
  display:flex; align-items:center; justify-content:center;
  margin-top:68px;
}
.hero-banner::before {
  content:''; position:absolute; inset:0;
  background: linear-gradient(135deg, rgba(13,13,20,0.85) 0%, rgba(26,26,46,0.6) 50%, rgba(13,13,20,0.85) 100%);
}
.hero-content {
  position:relative; z-index:2; text-align:center; padding:60px 20px;
  max-width:800px;
}
.hero-content h1 {
  font-size:3rem; font-weight:900; color:#fff; margin-bottom:16px;
  text-shadow: 0 2px 20px rgba(232,53,15,0.5);
}
.hero-content h1 span { color:var(--brand-red); }
.hero-content p {
  font-size:1.15rem; color:rgba(240,240,240,0.85); margin-bottom:30px;
  line-height:1.8;
}
.hero-btn {
  display:inline-block; padding:14px 40px; background:var(--brand-red);
  color:#fff; font-size:1.05rem; font-weight:600; border-radius:6px;
  transition: all .3s; box-shadow: 0 4px 20px rgba(232,53,15,0.4);
}
.hero-btn:hover {
  background:#c42a0a; transform:translateY(-2px);
  box-shadow: 0 6px 30px rgba(232,53,15,0.6);
  color:#fff;
}

/* ===== Section Common ===== */
.section { padding:70px 0; }
.section-alt { background: var(--card-bg); }

.section-header {
  text-align:center; margin-bottom:50px;
}
.section-header h2 {
  font-size:2rem; font-weight:800; color:#fff; margin-bottom:12px;
  position:relative; display:inline-block;
}
.section-header h2::after {
  content:''; display:block; width:60px; height:3px;
  background:var(--brand-red); margin:12px auto 0;
}
.section-header p { color:rgba(240,240,240,0.7); font-size:1rem; margin-top:10px; }

/* ===== Video Card Grid ===== */
.video-grid {
  display:grid; grid-template-columns:repeat(auto-fill, minmax(320px, 1fr));
  gap:24px;
}

.video-card {
  background:var(--card-bg); border-radius:10px; overflow:hidden;
  border:1px solid rgba(232,53,15,0.1); transition:all .3s;
}
.video-card:hover {
  transform:translateY(-4px); box-shadow:var(--shadow-glow);
  border-color:var(--border-subtle);
}

.video-thumb {
  position:relative; overflow:hidden; aspect-ratio:16/9;
}
.video-thumb img {
  width:100%; height:100%; object-fit:cover; transition:transform .5s;
}
.video-card:hover .video-thumb img { transform:scale(1.05); }

.play-btn {
  position:absolute; top:50%; left:50%; transform:translate(-50%,-50%);
  width:60px; height:60px; background:rgba(232,53,15,0.85);
  border-radius:50%; display:flex; align-items:center; justify-content:center;
  opacity:0; transition:opacity .3s;
}
.video-card:hover .play-btn { opacity:1; }
.play-btn::after {
  content:''; width:0; height:0;
  border-left:20px solid #fff; border-top:12px solid transparent;
  border-bottom:12px solid transparent; margin-left:4px;
}

.video-info { padding:16px; }
.video-info h3 { font-size:1.05rem; font-weight:700; color:#fff; margin-bottom:8px; }
.video-meta {
  display:flex; gap:16px; font-size:.82rem; color:rgba(240,240,240,0.5);
}
.video-meta span { display:flex; align-items:center; gap:4px; }
.video-tag {
  display:inline-block; padding:2px 10px; background:rgba(232,53,15,0.15);
  color:var(--brand-red); font-size:.75rem; border-radius:20px; margin-top:8px;
}

/* ===== AI Section ===== */
.ai-grid {
  display:grid; grid-template-columns:repeat(auto-fill, minmax(280px, 1fr));
  gap:24px;
}
.ai-card {
  background:var(--card-bg); border-radius:10px; padding:30px;
  border:1px solid rgba(245,166,35,0.15); text-align:center;
  transition:all .3s;
}
.ai-card:hover {
  border-color:var(--brand-gold);
  box-shadow:0 4px 30px rgba(245,166,35,0.15);
}
.ai-icon {
  width:64px; height:64px; margin:0 auto 16px;
  background:rgba(245,166,35,0.1); border-radius:50%;
  display:flex; align-items:center; justify-content:center;
  font-size:1.8rem;
}
.ai-card h3 { font-size:1.1rem; color:var(--brand-gold); margin-bottom:10px; }
.ai-card p { font-size:.9rem; color:rgba(240,240,240,0.65); }

/* ===== Expert Section ===== */
.expert-grid {
  display:grid; grid-template-columns:repeat(auto-fill, minmax(260px, 1fr));
  gap:24px;
}
.expert-card {
  background:var(--card-bg); border-radius:10px; padding:30px;
  text-align:center; border:1px solid rgba(232,53,15,0.1);
  transition:all .3s;
}
.expert-card:hover { border-color:var(--border-subtle); box-shadow:var(--shadow-glow); }
.expert-avatar {
  width:120px; height:120px; border-radius:50%; margin:0 auto 16px;
  overflow:hidden; border:3px solid var(--brand-red);
}
.expert-avatar img { width:100%; height:100%; object-fit:cover; }
.expert-card h3 { font-size:1.1rem; color:#fff; margin-bottom:4px; }
.expert-card .role { color:var(--brand-gold); font-size:.85rem; margin-bottom:10px; }
.expert-card p { font-size:.85rem; color:rgba(240,240,240,0.6); margin-bottom:14px; }
.expert-links { display:flex; gap:10px; justify-content:center; }
.expert-links a {
  padding:6px 16px; border:1px solid var(--brand-red); border-radius:4px;
  font-size:.82rem; color:var(--brand-red); transition:all .3s;
}
.expert-links a:hover { background:var(--brand-red); color:#fff; }

/* ===== Partner Logos ===== */
.partner-wall {
  display:flex; flex-wrap:wrap; justify-content:center; gap:30px;
  align-items:center;
}
.partner-wall .partner-item {
  padding:16px 28px; background:var(--card-bg); border-radius:8px;
  font-size:1.1rem; font-weight:700; color:rgba(240,240,240,0.6);
  border:1px solid rgba(232,53,15,0.1); transition:all .3s;
}
.partner-wall .partner-item:hover {
  color:var(--brand-red); border-color:var(--brand-red);
}

/* ===== FAQ ===== */
.faq-list { max-width:800px; margin:0 auto; }
.faq-item {
  background:var(--card-bg); border-radius:8px; margin-bottom:12px;
  border:1px solid rgba(232,53,15,0.1); overflow:hidden;
}
.faq-question {
  padding:18px 24px; cursor:pointer; display:flex;
  justify-content:space-between; align-items:center;
  font-weight:600; color:#fff; transition:background .3s;
}
.faq-question:hover { background:rgba(232,53,15,0.05); }
.faq-question .arrow { transition:transform .3s; color:var(--brand-red); }
.faq-item.open .faq-question .arrow { transform:rotate(180deg); }
.faq-answer {
  padding:0 24px; max-height:0; overflow:hidden; transition:all .4s ease;
  color:rgba(240,240,240,0.7); font-size:.92rem; line-height:1.8;
}
.faq-item.open .faq-answer { padding:0 24px 18px; max-height:500px; }

/* ===== Reviews ===== */
.review-grid {
  display:grid; grid-template-columns:repeat(auto-fill, minmax(280px, 1fr));
  gap:24px;
}
.review-card {
  background:var(--card-bg); border-radius:10px; padding:24px;
  border:1px solid rgba(232,53,15,0.1);
}
.review-stars { color:var(--brand-gold); font-size:1rem; margin-bottom:10px; letter-spacing:2px; }
.review-card p { font-size:.92rem; color:rgba(240,240,240,0.75); margin-bottom:14px; line-height:1.7; }
.review-author { font-size:.85rem; color:var(--brand-gold); font-weight:600; }

/* ===== Contact ===== */
.contact-grid {
  display:grid; grid-template-columns:repeat(auto-fill, minmax(300px, 1fr));
  gap:30px;
}
.contact-block {
  background:var(--card-bg); border-radius:10px; padding:30px;
  border:1px solid rgba(232,53,15,0.1);
}
.contact-block h3 { font-size:1.15rem; color:var(--brand-red); margin-bottom:16px; }
.contact-block p { font-size:.9rem; color:rgba(240,240,240,0.7); margin-bottom:8px; }

/* ===== How-To Guide ===== */
.howto-steps {
  display:grid; grid-template-columns:repeat(auto-fill, minmax(240px, 1fr));
  gap:24px; max-width:1000px; margin:0 auto;
}
.howto-step {
  text-align:center; padding:30px 20px;
  background:var(--card-bg); border-radius:10px;
  border:1px solid rgba(232,53,15,0.1);
}
.step-num {
  width:48px; height:48px; line-height:48px; border-radius:50%;
  background:var(--brand-red); color:#fff; font-size:1.3rem; font-weight:800;
  margin:0 auto 14px; text-align:center;
}
.howto-step h4 { color:#fff; margin-bottom:8px; }
.howto-step p { font-size:.85rem; color:rgba(240,240,240,0.6); }

/* ===== Community Tags ===== */
.community-tags {
  display:flex; flex-wrap:wrap; gap:12px; justify-content:center; margin-top:20px;
}
.community-tags span {
  padding:8px 20px; background:rgba(232,53,15,0.1);
  border:1px solid var(--border-subtle); border-radius:20px;
  font-size:.88rem; color:var(--text-light); transition:all .3s;
}
.community-tags span:hover {
  background:var(--brand-red); color:#fff;
}

/* ===== Share Bar ===== */
.share-bar {
  display:flex; gap:12px; justify-content:center; flex-wrap:wrap;
  padding:20px 0;
}
.share-bar a {
  padding:10px 22px; background:var(--card-bg); border-radius:6px;
  color:var(--text-light); font-size:.9rem; border:1px solid rgba(232,53,15,0.1);
  transition:all .3s;
}
.share-bar a:hover { background:var(--brand-red); color:#fff; border-color:var(--brand-red); }

/* ===== Footer ===== */
.site-footer {
  background:var(--brand-dark); padding:50px 0 20px;
  border-top:2px solid var(--brand-red);
}
.footer-grid {
  display:grid; grid-template-columns:repeat(auto-fit, minmax(220px, 1fr));
  gap:30px; margin-bottom:30px;
}
.footer-col h4 { color:var(--brand-red); font-size:1rem; margin-bottom:14px; }
.footer-col p, .footer-col a { font-size:.88rem; color:rgba(240,240,240,0.6); display:block; margin-bottom:6px; }
.footer-col a:hover { color:var(--brand-red); }
.footer-qr { display:flex; gap:20px; margin-top:10px; }
.footer-qr img { width:120px; height:120px; border-radius:6px; }

.footer-bottom {
  text-align:center; padding-top:20px;
  border-top:1px solid rgba(240,240,240,0.1);
  font-size:.82rem; color:rgba(240,240,240,0.4);
}

/* ===== Breadcrumb ===== */
.breadcrumb {
  padding:14px 0; font-size:.85rem; color:rgba(240,240,240,0.5);
  margin-top:68px;
}
.breadcrumb a { color:var(--brand-gold); }
.breadcrumb span { margin:0 8px; }

/* ===== Inner Page Content ===== */
.page-content { padding:40px 0 70px; }
.page-content h1 {
  font-size:2.2rem; font-weight:800; color:#fff; margin-bottom:20px;
}
.page-content h2 {
  font-size:1.6rem; font-weight:700; color:var(--brand-red); margin:30px 0 14px;
}
.page-content p {
  font-size:1rem; color:rgba(240,240,240,0.75); margin-bottom:16px; line-height:1.8;
}

/* ===== Mobile Nav Toggle ===== */
.nav-toggle { display:none; background:none; border:none; cursor:pointer; padding:8px; }
.nav-toggle span {
  display:block; width:24px; height:2px; background:var(--text-light);
  margin:5px 0; transition:all .3s;
}

/* ===== Responsive ===== */
@media (max-width:768px) {
  .nav-toggle { display:block; }
  .main-nav {
    display:none; position:absolute; top:100%; left:0; width:100%;
    background:rgba(13,13,20,0.98); flex-direction:column; padding:10px 0;
  }
  .main-nav.open { display:flex; }
  .main-nav a { padding:12px 20px; border-bottom:1px solid rgba(240,240,240,0.05); }

  .hero-content h1 { font-size:2rem; }
  .hero-banner { min-height:50vh; }

  .video-grid { grid-template-columns:1fr; }
  .expert-grid { grid-template-columns:repeat(2, 1fr); }
  .footer-grid { grid-template-columns:1fr; }
  .contact-grid { grid-template-columns:1fr; }
}

@media (max-width:480px) {
  .expert-grid { grid-template-columns:1fr; }
  .header-inner { padding:8px 12px; }
  .logo-link img { height:36px; }
  .logo-text { font-size:1.2rem; }
}

/* ===== Lazy Load ===== */
img[data-src] { opacity:0; transition:opacity .5s; }
img[data-src].loaded { opacity:1; }

/* ===== MCP Frontend Placeholder ===== */
.mcp-widget {
  background:var(--card-bg); border-radius:10px; padding:20px;
  border:1px solid rgba(245,166,35,0.2); margin-top:20px;
  text-align:center;
}
.mcp-widget h4 { color:var(--brand-gold); margin-bottom:10px; }
.mcp-widget .mcp-status {
  display:inline-block; padding:6px 16px; background:rgba(245,166,35,0.1);
  border-radius:20px; font-size:.85rem; color:var(--brand-gold);
}