/* ============================================
   51视频 - 原创样式表
   品牌色系：深紫 #6C3CE1 / 粉红 #FF6B9D / 青绿 #00D4AA
   背景色系：#0D0B1A / #1A1730 / #241F3D
   ============================================ */

/* --- Reset & Base --- */
*, *::before, *::after { 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: #0D0B1A;
  color: #d4d0e8;
  line-height: 1.7;
  overflow-x: hidden;
}
a { color: #b89aff; text-decoration: none; transition: color .25s; }
a:hover { color: #FF6B9D; }
img { max-width: 100%; height: auto; display: block; }
ul, ol { list-style: none; }
h1,h2,h3,h4,h5,h6 { color: #fff; font-weight: 700; line-height: 1.3; }

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

/* --- Header / Navigation --- */
.site-header {
  position: fixed; top: 0; left: 0; width: 100%; z-index: 1000;
  background: rgba(13,11,26,.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(108,60,225,.25);
  transition: background .3s;
}
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  max-width: 1200px; margin: 0 auto; padding: 0 20px; height: 68px;
}
.logo-link { display: flex; align-items: center; gap: 10px; }
.logo-link img { height: 42px; width: auto; }
.logo-text { font-size: 1.35rem; font-weight: 800; background: linear-gradient(135deg, #6C3CE1, #FF6B9D); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; }
.main-nav { display: flex; gap: 6px; }
.main-nav a {
  padding: 8px 16px; border-radius: 8px; font-size: .92rem; font-weight: 500;
  color: #c4bfe0; transition: all .25s;
}
.main-nav a:hover, .main-nav a.active {
  background: rgba(108,60,225,.18); color: #fff;
}
.mobile-toggle { display: none; background: none; border: none; color: #fff; font-size: 1.5rem; cursor: pointer; }

/* --- Search Bar --- */
.search-bar-wrap {
  background: linear-gradient(135deg, rgba(108,60,225,.12), rgba(255,107,157,.08));
  padding: 14px 0;
  border-bottom: 1px solid rgba(108,60,225,.15);
  margin-top: 68px;
}
.search-bar {
  display: flex; max-width: 600px; margin: 0 auto;
  background: #1A1730; border: 1px solid rgba(108,60,225,.35);
  border-radius: 28px; overflow: hidden;
}
.search-bar input {
  flex: 1; padding: 10px 22px; background: transparent; border: none;
  color: #fff; font-size: .95rem; outline: none;
}
.search-bar input::placeholder { color: #7a7494; }
.search-bar button {
  padding: 10px 26px; background: linear-gradient(135deg, #6C3CE1, #8B5CF6);
  border: none; color: #fff; font-weight: 600; cursor: pointer;
  border-radius: 0 28px 28px 0; transition: opacity .25s;
}
.search-bar button:hover { opacity: .85; }

/* --- Hero Section --- */
.hero-section {
  position: relative; overflow: hidden;
  padding: 80px 0 60px;
  background: linear-gradient(180deg, #0D0B1A 0%, #1a1040 50%, #0D0B1A 100%);
}
.hero-section::before {
  content: ''; position: absolute; top: -50%; left: -50%;
  width: 200%; height: 200%;
  background: radial-gradient(circle at 30% 40%, rgba(108,60,225,.15) 0%, transparent 50%),
              radial-gradient(circle at 70% 60%, rgba(255,107,157,.1) 0%, transparent 50%);
  animation: heroGlow 8s ease-in-out infinite alternate;
}
@keyframes heroGlow {
  0% { transform: translate(0, 0); }
  100% { transform: translate(-3%, 3%); }
}
.hero-content { position: relative; z-index: 2; text-align: center; }
.hero-content h1 { font-size: 2.6rem; margin-bottom: 16px; }
.hero-content h1 span { background: linear-gradient(135deg, #6C3CE1, #FF6B9D, #00D4AA); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; }
.hero-content p { font-size: 1.1rem; color: #b8b5c8; max-width: 680px; margin: 0 auto 30px; }
.hero-banner-img { max-width: 900px; margin: 0 auto; border-radius: 16px; box-shadow: 0 20px 60px rgba(108,60,225,.25); }
.hero-tags { display: flex; flex-wrap: wrap; justify-content: center; gap: 10px; margin-top: 28px; }
.hero-tags span {
  padding: 6px 18px; border-radius: 20px; font-size: .82rem;
  background: rgba(108,60,225,.15); border: 1px solid rgba(108,60,225,.3);
  color: #c4bfe0;
}

/* --- Section Common --- */
.section { padding: 70px 0; }
.section-title {
  text-align: center; margin-bottom: 48px;
}
.section-title h2 { font-size: 2rem; margin-bottom: 10px; }
.section-title h2 span { color: #6C3CE1; }
.section-title p { color: #9590b0; font-size: 1rem; }
.section-alt { background: #110F22; }

/* --- Video Card Grid --- */
.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 24px;
}
.video-card {
  background: #1A1730; border-radius: 14px; overflow: hidden;
  border: 1px solid rgba(108,60,225,.12);
  transition: transform .3s, box-shadow .3s;
  cursor: pointer;
}
.video-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 16px 40px rgba(108,60,225,.2);
}
.video-card .thumb {
  position: relative; overflow: hidden;
  aspect-ratio: 3/4;
}
.video-card .thumb img {
  width: 100%; height: 100%; object-fit: cover;
  transition: transform .4s;
}
.video-card:hover .thumb img { transform: scale(1.06); }
.video-card .play-btn {
  position: absolute; top: 50%; left: 50%;
  transform: translate(-50%, -50%) scale(0);
  width: 56px; height: 56px; border-radius: 50%;
  background: rgba(108,60,225,.85);
  display: flex; align-items: center; justify-content: center;
  transition: transform .3s;
}
.video-card .play-btn::after {
  content: ''; width: 0; height: 0;
  border-style: solid; border-width: 10px 0 10px 18px;
  border-color: transparent transparent transparent #fff;
  margin-left: 3px;
}
.video-card:hover .play-btn { transform: translate(-50%, -50%) scale(1); }
.video-card .card-info { padding: 14px 16px; }
.video-card .card-title { font-size: .95rem; color: #fff; margin-bottom: 6px; font-weight: 600; }
.video-card .card-meta { display: flex; gap: 14px; font-size: .78rem; color: #8a85a5; }
.video-card .card-meta span { display: flex; align-items: center; gap: 4px; }
.video-card .card-tags { display: flex; gap: 6px; margin-top: 8px; flex-wrap: wrap; }
.video-card .card-tags span {
  font-size: .7rem; padding: 2px 10px; border-radius: 10px;
  background: rgba(108,60,225,.12); color: #b89aff;
}

/* --- Service Modules --- */
.service-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px;
}
.service-card {
  background: linear-gradient(145deg, #1A1730, #201c38);
  border-radius: 16px; padding: 32px 24px;
  border: 1px solid rgba(108,60,225,.12);
  transition: transform .3s, border-color .3s;
  text-align: center;
}
.service-card:hover {
  transform: translateY(-4px);
  border-color: rgba(108,60,225,.4);
}
.service-icon {
  width: 64px; height: 64px; margin: 0 auto 18px;
  border-radius: 16px; display: flex; align-items: center; justify-content: center;
  font-size: 1.8rem;
}
.service-icon.purple { background: rgba(108,60,225,.18); }
.service-icon.pink { background: rgba(255,107,157,.18); }
.service-icon.teal { background: rgba(0,212,170,.18); }
.service-card h3 { font-size: 1.1rem; margin-bottom: 10px; }
.service-card p { font-size: .88rem; color: #9590b0; }

/* --- AI Section --- */
.ai-section-inner {
  display: flex; align-items: center; gap: 48px;
}
.ai-text { flex: 1; }
.ai-text h2 { font-size: 1.8rem; margin-bottom: 16px; }
.ai-text p { color: #9590b0; margin-bottom: 14px; }
.ai-img { flex: 1; border-radius: 16px; overflow: hidden; }
.ai-features { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 20px; }
.ai-feat-tag {
  padding: 8px 18px; border-radius: 10px;
  background: rgba(0,212,170,.1); border: 1px solid rgba(0,212,170,.25);
  color: #00D4AA; font-size: .85rem;
}

/* --- Expert Section --- */
.expert-grid {
  display: grid; grid-template-columns: repeat(5, 1fr); gap: 24px;
}
.expert-card {
  background: #1A1730; border-radius: 16px; padding: 28px 20px;
  text-align: center; border: 1px solid rgba(108,60,225,.1);
  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 14px; border: 3px solid rgba(108,60,225,.3);
}
.expert-card h4 { font-size: 1rem; margin-bottom: 4px; }
.expert-card .role { font-size: .82rem; color: #FF6B9D; margin-bottom: 10px; }
.expert-card p { font-size: .8rem; color: #9590b0; margin-bottom: 14px; }
.expert-card .btn-group { display: flex; gap: 8px; justify-content: center; }
.btn-sm {
  padding: 6px 14px; border-radius: 8px; font-size: .78rem; font-weight: 500;
  border: 1px solid rgba(108,60,225,.3); color: #b89aff;
  transition: all .25s; cursor: pointer; background: transparent;
}
.btn-sm:hover { background: rgba(108,60,225,.15); color: #fff; }
.btn-sm.primary { background: rgba(108,60,225,.2); border-color: #6C3CE1; }

/* --- Partner Logos --- */
.partner-wall {
  display: flex; flex-wrap: wrap; justify-content: center; gap: 32px;
  padding: 20px 0;
}
.partner-logo {
  width: 120px; height: 60px; background: #1A1730; border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  border: 1px solid rgba(108,60,225,.1); color: #7a7494; font-size: .85rem;
  font-weight: 600;
}

/* --- FAQ Section --- */
.faq-list { max-width: 800px; margin: 0 auto; }
.faq-item {
  background: #1A1730; border-radius: 12px; margin-bottom: 12px;
  border: 1px solid rgba(108,60,225,.1); overflow: hidden;
}
.faq-q {
  padding: 18px 24px; cursor: pointer; display: flex;
  justify-content: space-between; align-items: center;
  font-weight: 600; color: #e0ddf0; font-size: .95rem;
  transition: background .25s;
}
.faq-q:hover { background: rgba(108,60,225,.08); }
.faq-q .arrow { transition: transform .3s; color: #6C3CE1; font-size: 1.2rem; }
.faq-item.open .faq-q .arrow { transform: rotate(180deg); }
.faq-a {
  max-height: 0; overflow: hidden; transition: max-height .35s ease;
  padding: 0 24px; color: #9590b0; font-size: .9rem;
}
.faq-item.open .faq-a { max-height: 300px; padding: 0 24px 18px; }

/* --- Reviews --- */
.review-grid {
  display: grid; grid-template-columns: repeat(2, 1fr); gap: 24px;
}
.review-card {
  background: #1A1730; border-radius: 14px; padding: 24px;
  border: 1px solid rgba(108,60,225,.1);
}
.review-header { display: flex; align-items: center; gap: 12px; margin-bottom: 12px; }
.review-avatar {
  width: 44px; height: 44px; border-radius: 50%;
  background: linear-gradient(135deg, #6C3CE1, #FF6B9D);
  display: flex; align-items: center; justify-content: center;
  color: #fff; font-weight: 700; font-size: 1rem;
}
.review-name { font-weight: 600; color: #fff; font-size: .92rem; }
.review-date { font-size: .78rem; color: #7a7494; }
.review-stars { color: #FFB800; font-size: .9rem; margin-bottom: 8px; }
.review-text { font-size: .88rem; color: #b8b5c8; line-height: 1.65; }

/* --- Community Section --- */
.community-features {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px;
}
.comm-feat {
  background: linear-gradient(145deg, #1A1730, #1f1a38);
  border-radius: 14px; padding: 28px 22px;
  border: 1px solid rgba(255,107,157,.1);
  transition: transform .3s;
}
.comm-feat:hover { transform: translateY(-3px); }
.comm-feat h4 { color: #FF6B9D; margin-bottom: 10px; font-size: 1rem; }
.comm-feat p { font-size: .85rem; color: #9590b0; }

/* --- How-To Guide --- */
.howto-steps {
  display: flex; gap: 24px; justify-content: center; flex-wrap: wrap;
}
.howto-step {
  background: #1A1730; border-radius: 14px; padding: 28px 24px;
  flex: 1; min-width: 220px; max-width: 280px; text-align: center;
  border: 1px solid rgba(108,60,225,.1);
}
.step-num {
  width: 48px; height: 48px; border-radius: 50%; margin: 0 auto 14px;
  background: linear-gradient(135deg, #6C3CE1, #8B5CF6);
  display: flex; align-items: center; justify-content: center;
  color: #fff; font-weight: 800; font-size: 1.2rem;
}
.howto-step h4 { margin-bottom: 8px; font-size: .95rem; }
.howto-step p { font-size: .82rem; color: #9590b0; }

/* --- Contact Section --- */
.contact-grid {
  display: grid; grid-template-columns: repeat(2, 1fr); gap: 32px;
}
.contact-card {
  background: #1A1730; border-radius: 16px; padding: 32px;
  border: 1px solid rgba(108,60,225,.1);
}
.contact-card h3 { font-size: 1.15rem; margin-bottom: 16px; color: #fff; }
.contact-item { display: flex; gap: 10px; margin-bottom: 12px; font-size: .9rem; color: #b8b5c8; }
.contact-item strong { color: #c4bfe0; min-width: 80px; }

/* --- Share Buttons --- */
.share-bar {
  display: flex; gap: 12px; justify-content: center; padding: 20px 0;
}
.share-btn {
  padding: 10px 22px; border-radius: 10px; font-size: .85rem;
  font-weight: 600; border: none; cursor: pointer; transition: opacity .25s;
  color: #fff;
}
.share-btn.wechat { background: #07C160; }
.share-btn.weibo { background: #E6162D; }
.share-btn.douyin { background: #161823; border: 1px solid #444; }
.share-btn.bilibili { background: #00A1D6; }
.share-btn:hover { opacity: .8; }

/* --- Footer --- */
.site-footer {
  background: #08071A; border-top: 1px solid rgba(108,60,225,.15);
  padding: 48px 0 24px;
}
.footer-inner {
  display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 32px;
  max-width: 1200px; margin: 0 auto; padding: 0 20px;
}
.footer-brand .logo-text { font-size: 1.2rem; margin-bottom: 10px; display: inline-block; }
.footer-brand p { font-size: .82rem; color: #7a7494; margin-bottom: 12px; }
.footer-col h5 { color: #fff; font-size: .92rem; margin-bottom: 14px; }
.footer-col a { display: block; font-size: .82rem; color: #7a7494; margin-bottom: 8px; }
.footer-col a:hover { color: #b89aff; }
.footer-qr { display: flex; gap: 16px; margin-top: 14px; }
.footer-qr img { width: 100px; height: 100px; border-radius: 8px; }
.footer-bottom {
  text-align: center; padding-top: 28px; margin-top: 28px;
  border-top: 1px solid rgba(108,60,225,.1);
  font-size: .8rem; color: #5a5674;
}

/* --- Breadcrumb --- */
.breadcrumb {
  padding: 14px 0; font-size: .82rem; color: #7a7494;
  margin-top: 68px;
}
.breadcrumb a { color: #b89aff; }
.breadcrumb span { margin: 0 8px; }

/* --- Page Banner --- */
.page-banner {
  padding: 60px 0 40px;
  background: linear-gradient(180deg, #1a1040, #0D0B1A);
  text-align: center;
  margin-top: 68px;
}
.page-banner h1 { font-size: 2.2rem; margin-bottom: 12px; }
.page-banner p { color: #9590b0; font-size: 1rem; }

/* --- Content Area --- */
.content-area {
  padding: 48px 0;
}
.content-area p { margin-bottom: 16px; font-size: .95rem; }
.content-area h2 { font-size: 1.6rem; margin: 32px 0 16px; }
.content-area h3 { font-size: 1.3rem; margin: 24px 0 12px; }

/* --- Buttons --- */
.btn-primary {
  display: inline-block; padding: 12px 32px; border-radius: 10px;
  background: linear-gradient(135deg, #6C3CE1, #8B5CF6);
  color: #fff; font-weight: 600; font-size: .95rem;
  border: none; cursor: pointer; transition: opacity .25s;
}
.btn-primary:hover { opacity: .85; color: #fff; }
.btn-outline {
  display: inline-block; padding: 12px 32px; border-radius: 10px;
  border: 1px solid rgba(108,60,225,.4); color: #b89aff;
  font-weight: 600; font-size: .95rem; cursor: pointer;
  transition: all .25s; background: transparent;
}
.btn-outline:hover { background: rgba(108,60,225,.15); color: #fff; }

/* --- Responsive --- */
@media (max-width: 1024px) {
  .service-grid { grid-template-columns: repeat(2, 1fr); }
  .expert-grid { grid-template-columns: repeat(3, 1fr); }
  .footer-inner { grid-template-columns: 1fr 1fr; }
  .ai-section-inner { flex-direction: column; }
}
@media (max-width: 768px) {
  .main-nav { display: none; position: absolute; top: 68px; left: 0; width: 100%; background: #0D0B1A; flex-direction: column; padding: 16px; border-bottom: 1px solid rgba(108,60,225,.2); }
  .main-nav.open { display: flex; }
  .mobile-toggle { display: block; }
  .hero-content h1 { font-size: 1.8rem; }
  .video-grid { grid-template-columns: repeat(2, 1fr); gap: 14px; }
  .service-grid, .community-features { grid-template-columns: 1fr; }
  .expert-grid { grid-template-columns: repeat(2, 1fr); }
  .review-grid { grid-template-columns: 1fr; }
  .contact-grid { grid-template-columns: 1fr; }
  .footer-inner { grid-template-columns: 1fr; }
  .howto-steps { flex-direction: column; align-items: center; }
  .section { padding: 40px 0; }
}
@media (max-width: 480px) {
  .video-grid { grid-template-columns: 1fr; }
  .expert-grid { grid-template-columns: 1fr; }
}

/* --- Lazy Load --- */
img[loading="lazy"] { opacity: 0; transition: opacity .4s; }
img[loading="lazy"].loaded, img[loading="lazy"][src] { opacity: 1; }

/* --- Animations --- */
.fade-in {
  opacity: 0; transform: translateY(24px);
  transition: opacity .6s, transform .6s;
}
.fade-in.visible { opacity: 1; transform: translateY(0); }