/* ============================================
   困困兔 - 汽车改装视频社区 (hzsdsy.cn)
   全新原创CSS - 赛博朋克暗黑风格
   配色：暗黑底(#0D0D0D) + 霓虹红(#FF2D55) + 电光蓝(#00D4FF) + 钢灰(#1A1A2E)
   ============================================ */

/* === CSS Variables === */
:root {
  --bg-primary: #0D0D0D;
  --bg-secondary: #1A1A2E;
  --bg-card: #16162A;
  --bg-hover: #222244;
  --neon-red: #FF2D55;
  --neon-blue: #00D4FF;
  --neon-purple: #A855F7;
  --text-primary: #F0F0F0;
  --text-secondary: #9CA3AF;
  --text-muted: #6B7280;
  --border-color: #2D2D4A;
  --gradient-hero: linear-gradient(135deg, #0D0D0D 0%, #1A1A2E 50%, #16082A 100%);
  --gradient-neon: linear-gradient(90deg, #FF2D55, #A855F7, #00D4FF);
  --shadow-neon: 0 0 20px rgba(255, 45, 85, 0.3);
  --shadow-blue: 0 0 20px rgba(0, 212, 255, 0.3);
  --radius: 12px;
  --radius-lg: 20px;
  --transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
}

/* === Reset & Base === */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', Arial, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  overflow-x: hidden;
}
a { color: var(--neon-blue); text-decoration: none; transition: var(--transition); }
a:hover { color: var(--neon-red); }
img { max-width: 100%; height: auto; display: block; }
ul, ol { list-style: none; }

/* === Container === */
.container { max-width: 1280px; margin: 0 auto; padding: 0 24px; }

/* === Header & Navigation === */
.site-header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  background: rgba(13, 13, 13, 0.92);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-color);
  transition: var(--transition);
}
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  height: 72px; max-width: 1280px; margin: 0 auto; padding: 0 24px;
}
.logo-link { display: flex; align-items: center; gap: 10px; }
.logo-link img { height: 40px; width: 40px; border-radius: 8px; }
.logo-text {
  font-size: 1.5rem; font-weight: 800; color: var(--text-primary);
  letter-spacing: 1px;
}
.logo-text span { color: var(--neon-red); }

.main-nav { display: flex; gap: 6px; }
.main-nav a {
  padding: 8px 16px; border-radius: 8px; font-size: 0.95rem;
  color: var(--text-secondary); font-weight: 500;
  transition: var(--transition);
}
.main-nav a:hover, .main-nav a.active {
  color: var(--neon-red); background: rgba(255, 45, 85, 0.1);
}

.mobile-toggle {
  display: none; background: none; border: none; cursor: pointer;
  width: 36px; height: 36px; position: relative;
}
.mobile-toggle span {
  display: block; width: 24px; height: 2px; background: var(--text-primary);
  position: absolute; left: 6px; transition: var(--transition);
}
.mobile-toggle span:nth-child(1) { top: 10px; }
.mobile-toggle span:nth-child(2) { top: 17px; }
.mobile-toggle span:nth-child(3) { top: 24px; }

/* === Hero Section === */
.hero-section {
  position: relative; min-height: 100vh; display: flex; align-items: center;
  background: var(--gradient-hero);
  overflow: hidden; padding-top: 72px;
}
.hero-bg {
  position: absolute; inset: 0; z-index: 0;
}
.hero-bg img {
  width: 100%; height: 100%; object-fit: cover; opacity: 0.25;
  filter: saturate(1.3);
}
.hero-bg::after {
  content: ''; position: absolute; inset: 0;
  background: linear-gradient(180deg, rgba(13,13,13,0.6) 0%, rgba(13,13,13,0.9) 100%);
}
.hero-content {
  position: relative; z-index: 2; text-align: center;
  max-width: 800px; margin: 0 auto; padding: 60px 24px;
}
.hero-badge {
  display: inline-block; padding: 6px 20px; border-radius: 50px;
  background: rgba(255, 45, 85, 0.15); border: 1px solid rgba(255, 45, 85, 0.4);
  color: var(--neon-red); font-size: 0.85rem; font-weight: 600;
  margin-bottom: 24px; letter-spacing: 2px;
}
.hero-content h1 {
  font-size: 3.2rem; font-weight: 900; line-height: 1.2;
  margin-bottom: 20px;
  background: var(--gradient-neon);
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero-content p {
  font-size: 1.15rem; color: var(--text-secondary);
  margin-bottom: 36px; line-height: 1.8;
}
.hero-stats {
  display: flex; justify-content: center; gap: 48px; margin-top: 40px;
}
.hero-stat { text-align: center; }
.hero-stat .num {
  font-size: 2.4rem; font-weight: 800; color: var(--neon-blue);
  display: block;
}
.hero-stat .label { font-size: 0.85rem; color: var(--text-muted); margin-top: 4px; }

/* === Search Box === */
.search-box {
  max-width: 560px; margin: 0 auto; position: relative;
}
.search-box input {
  width: 100%; padding: 16px 56px 16px 24px; border-radius: 50px;
  border: 1px solid var(--border-color); background: var(--bg-secondary);
  color: var(--text-primary); font-size: 1rem;
  transition: var(--transition);
}
.search-box input:focus {
  outline: none; border-color: var(--neon-red);
  box-shadow: var(--shadow-neon);
}
.search-box input::placeholder { color: var(--text-muted); }
.search-box button {
  position: absolute; right: 6px; top: 50%; transform: translateY(-50%);
  width: 44px; height: 44px; border-radius: 50%;
  background: var(--neon-red); border: none; cursor: pointer;
  color: #fff; font-size: 1.1rem; transition: var(--transition);
}
.search-box button:hover { background: #E0264B; box-shadow: var(--shadow-neon); }

/* === Section Common === */
.section {
  padding: 80px 0;
}
.section-dark { background: var(--bg-secondary); }
.section-title {
  text-align: center; margin-bottom: 56px;
}
.section-title h2 {
  font-size: 2.2rem; font-weight: 800; margin-bottom: 12px;
  color: var(--text-primary);
}
.section-title h2 .highlight { color: var(--neon-red); }
.section-title p {
  font-size: 1rem; color: var(--text-secondary); max-width: 600px; margin: 0 auto;
}
.neon-line {
  width: 80px; height: 3px; margin: 16px auto 0;
  background: var(--gradient-neon); border-radius: 2px;
}

/* === Video Card Grid === */
.video-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px;
}
.video-card {
  background: var(--bg-card); border-radius: var(--radius);
  overflow: hidden; border: 1px solid var(--border-color);
  transition: var(--transition); position: relative;
}
.video-card:hover {
  transform: translateY(-6px);
  border-color: var(--neon-red);
  box-shadow: var(--shadow-neon);
}
.video-thumb {
  position: relative; padding-top: 56.25%; overflow: hidden;
  background: #111;
}
.video-thumb video,
.video-thumb img {
  position: absolute; top: 0; left: 0; width: 100%; height: 100%;
  object-fit: cover; transition: var(--transition);
}
.video-thumb video { z-index: 1; }
.video-thumb img { z-index: 2; }
.video-card:hover .video-thumb img { opacity: 0.7; }
.video-poster {
  position: absolute; top: 0; left: 0; width: 100%; height: 100%;
  z-index: 3; display: flex; align-items: center; justify-content: center;
  background: rgba(0, 0, 0, 0.4); opacity: 0;
  transition: var(--transition); cursor: pointer;
}
.video-card:hover .video-poster { opacity: 1; }
.play-btn {
  width: 64px; height: 64px; border-radius: 50%;
  background: var(--neon-red); display: flex;
  align-items: center; justify-content: center;
  box-shadow: var(--shadow-neon);
  transition: var(--transition);
}
.play-btn::after {
  content: ''; width: 0; height: 0;
  border-left: 22px solid #fff; border-top: 14px solid transparent;
  border-bottom: 14px solid transparent; margin-left: 4px;
}
.video-card:hover .play-btn { transform: scale(1.15); }
.video-duration {
  position: absolute; bottom: 10px; right: 10px; z-index: 4;
  background: rgba(0,0,0,0.8); color: #fff; padding: 2px 8px;
  border-radius: 4px; font-size: 0.75rem;
}
.video-info { padding: 16px; }
.video-info h3 {
  font-size: 1rem; font-weight: 700; margin-bottom: 8px;
  color: var(--text-primary); line-height: 1.4;
  display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical;
  overflow: hidden;
}
.video-meta {
  display: flex; justify-content: space-between; align-items: center;
  font-size: 0.8rem; color: var(--text-muted);
}
.video-tag {
  display: inline-block; padding: 2px 10px; border-radius: 4px;
  background: rgba(255, 45, 85, 0.1); color: var(--neon-red);
  font-size: 0.75rem; font-weight: 600;
}

/* === Feature Cards === */
.feature-grid {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px;
}
.feature-card {
  background: var(--bg-card); border-radius: var(--radius);
  padding: 32px 24px; text-align: center;
  border: 1px solid var(--border-color);
  transition: var(--transition);
}
.feature-card:hover {
  border-color: var(--neon-blue);
  box-shadow: var(--shadow-blue);
  transform: translateY(-4px);
}
.feature-icon {
  width: 64px; height: 64px; border-radius: 16px; margin: 0 auto 20px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.8rem;
  background: linear-gradient(135deg, rgba(255,45,85,0.15), rgba(168,85,247,0.15));
}
.feature-card h3 {
  font-size: 1.1rem; font-weight: 700; margin-bottom: 10px;
  color: var(--text-primary);
}
.feature-card p {
  font-size: 0.9rem; color: var(--text-secondary); line-height: 1.6;
}

/* === Expert Section === */
.expert-grid {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px;
}
.expert-card {
  background: var(--bg-card); border-radius: var(--radius);
  overflow: hidden; border: 1px solid var(--border-color);
  text-align: center; transition: var(--transition);
}
.expert-card:hover {
  border-color: var(--neon-purple);
  box-shadow: 0 0 20px rgba(168, 85, 247, 0.3);
  transform: translateY(-4px);
}
.expert-avatar {
  width: 100%; height: 240px; overflow: hidden;
}
.expert-avatar img {
  width: 100%; height: 100%; object-fit: cover;
  transition: var(--transition);
}
.expert-card:hover .expert-avatar img { transform: scale(1.05); }
.expert-info { padding: 20px 16px; }
.expert-info h3 {
  font-size: 1.1rem; font-weight: 700; margin-bottom: 6px;
  color: var(--text-primary);
}
.expert-role {
  font-size: 0.85rem; color: var(--neon-red); font-weight: 600;
  margin-bottom: 8px;
}
.expert-desc {
  font-size: 0.85rem; color: var(--text-secondary); line-height: 1.5;
}
.expert-contact {
  font-size: 0.8rem; color: var(--text-muted); margin-top: 8px;
}

/* === Community Section === */
.community-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px;
}
.community-card {
  background: var(--bg-card); border-radius: var(--radius);
  padding: 28px; border: 1px solid var(--border-color);
  transition: var(--transition);
}
.community-card:hover {
  border-color: var(--neon-blue);
  box-shadow: var(--shadow-blue);
}
.community-card h3 {
  font-size: 1.1rem; font-weight: 700; margin-bottom: 10px;
  color: var(--text-primary);
}
.community-card p {
  font-size: 0.9rem; color: var(--text-secondary); line-height: 1.6;
}
.community-tag {
  display: inline-block; margin-top: 12px; padding: 4px 12px;
  background: rgba(0, 212, 255, 0.1); color: var(--neon-blue);
  border-radius: 4px; font-size: 0.8rem; font-weight: 600;
}

/* === FAQ Section === */
.faq-list { max-width: 800px; margin: 0 auto; }
.faq-item {
  background: var(--bg-card); border-radius: var(--radius);
  margin-bottom: 12px; border: 1px solid var(--border-color);
  overflow: hidden; transition: var(--transition);
}
.faq-item:hover { border-color: var(--neon-red); }
.faq-question {
  padding: 20px 24px; cursor: pointer; display: flex;
  justify-content: space-between; align-items: center;
  font-weight: 700; font-size: 1rem; color: var(--text-primary);
}
.faq-question::after {
  content: '+'; font-size: 1.4rem; color: var(--neon-red);
  transition: var(--transition);
}
.faq-item.active .faq-question::after { content: '-'; }
.faq-answer {
  max-height: 0; overflow: hidden; transition: max-height 0.4s ease;
}
.faq-answer p {
  padding: 0 24px 20px; font-size: 0.95rem;
  color: var(--text-secondary); line-height: 1.7;
}
.faq-item.active .faq-answer { max-height: 300px; }

/* === Review Section === */
.review-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px;
}
.review-card {
  background: var(--bg-card); border-radius: var(--radius);
  padding: 28px; border: 1px solid var(--border-color);
}
.review-stars { color: #FFB800; font-size: 1rem; margin-bottom: 12px; letter-spacing: 2px; }
.review-text {
  font-size: 0.95rem; color: var(--text-secondary);
  line-height: 1.7; margin-bottom: 16px; font-style: italic;
}
.review-author {
  font-size: 0.85rem; font-weight: 700; color: var(--text-primary);
}
.review-date { font-size: 0.8rem; color: var(--text-muted); }

/* === Partner Section === */
.partner-grid {
  display: flex; flex-wrap: wrap; justify-content: center; gap: 32px;
  align-items: center;
}
.partner-item {
  padding: 16px 28px; background: var(--bg-card);
  border-radius: var(--radius); border: 1px solid var(--border-color);
  font-size: 1rem; font-weight: 700; color: var(--text-muted);
  transition: var(--transition);
}
.partner-item:hover { color: var(--neon-blue); border-color: var(--neon-blue); }

/* === Join Guide === */
.join-steps {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px;
}
.join-step {
  text-align: center; padding: 32px 20px;
  background: var(--bg-card); border-radius: var(--radius);
  border: 1px solid var(--border-color);
}
.step-num {
  width: 48px; height: 48px; border-radius: 50%; margin: 0 auto 16px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.2rem; font-weight: 800;
  background: var(--gradient-neon); color: #fff;
}
.join-step h3 {
  font-size: 1rem; font-weight: 700; margin-bottom: 8px;
  color: var(--text-primary);
}
.join-step p { font-size: 0.85rem; color: var(--text-secondary); }

/* === Share Section === */
.share-section { text-align: center; padding: 40px 0; }
.share-btns { display: flex; justify-content: center; gap: 16px; margin-top: 16px; }
.share-btn {
  padding: 10px 24px; border-radius: 8px; font-size: 0.9rem;
  font-weight: 600; cursor: pointer; border: 1px solid var(--border-color);
  background: var(--bg-card); color: var(--text-secondary);
  transition: var(--transition);
}
.share-btn:hover { color: var(--neon-red); border-color: var(--neon-red); }

/* === Footer === */
.site-footer {
  background: var(--bg-secondary); border-top: 1px solid var(--border-color);
  padding: 60px 0 0;
}
.footer-grid {
  display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px;
  margin-bottom: 40px;
}
.footer-brand .logo-link { margin-bottom: 16px; }
.footer-brand p {
  font-size: 0.9rem; color: var(--text-secondary); line-height: 1.7;
}
.footer-col h4 {
  font-size: 1rem; font-weight: 700; margin-bottom: 16px;
  color: var(--text-primary);
}
.footer-col a {
  display: block; padding: 4px 0; font-size: 0.9rem;
  color: var(--text-secondary);
}
.footer-col a:hover { color: var(--neon-red); }
.footer-qrcode {
  display: flex; gap: 16px; margin-top: 16px;
}
.footer-qrcode img {
  width: 100px; height: 100px; border-radius: 8px;
  border: 1px solid var(--border-color);
}
.footer-stats {
  display: flex; justify-content: center; gap: 48px;
  padding: 24px 0; border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 24px;
}
.footer-stat { text-align: center; }
.footer-stat .num {
  font-size: 1.5rem; font-weight: 800; color: var(--neon-red);
}
.footer-stat .label {
  font-size: 0.8rem; color: var(--text-muted); margin-top: 4px;
}
.footer-bottom {
  text-align: center; padding: 20px 0;
  border-top: 1px solid var(--border-color);
  font-size: 0.85rem; color: var(--text-muted);
}
.footer-bottom a { color: var(--text-muted); }
.footer-bottom a:hover { color: var(--neon-red); }

/* === Breadcrumb === */
.breadcrumb {
  padding: 100px 0 20px; font-size: 0.85rem; color: var(--text-muted);
}
.breadcrumb a { color: var(--text-secondary); }
.breadcrumb a:hover { color: var(--neon-red); }
.breadcrumb span { margin: 0 8px; }

/* === Back to Top === */
.back-top {
  position: fixed; bottom: 32px; right: 32px; z-index: 999;
  width: 48px; height: 48px; border-radius: 50%;
  background: var(--neon-red); color: #fff; border: none;
  cursor: pointer; font-size: 1.2rem; display: none;
  align-items: center; justify-content: center;
  box-shadow: var(--shadow-neon); transition: var(--transition);
}
.back-top:hover { transform: translateY(-4px); }
.back-top.show { display: flex; }

/* === Lazy Load === */
img[data-src] { opacity: 0; transition: opacity 0.5s ease; }
img[data-src].loaded { opacity: 1; }

/* === Page Banner (Inner Pages) === */
.page-banner {
  padding: 120px 0 60px;
  background: var(--gradient-hero);
  text-align: center;
}
.page-banner h1 {
  font-size: 2.4rem; font-weight: 800; margin-bottom: 12px;
  color: var(--text-primary);
}
.page-banner p {
  font-size: 1rem; color: var(--text-secondary);
}

/* === Responsive === */
@media (max-width: 1024px) {
  .video-grid { grid-template-columns: repeat(2, 1fr); }
  .feature-grid { grid-template-columns: repeat(2, 1fr); }
  .expert-grid { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .join-steps { grid-template-columns: repeat(2, 1fr); }
  .hero-content h1 { font-size: 2.4rem; }
}

@media (max-width: 768px) {
  .main-nav { display: none; }
  .mobile-toggle { display: block; }
  .main-nav.open {
    display: flex; flex-direction: column;
    position: absolute; top: 72px; left: 0; right: 0;
    background: rgba(13, 13, 13, 0.98); padding: 16px;
    border-bottom: 1px solid var(--border-color);
  }
  .hero-content h1 { font-size: 2rem; }
  .hero-stats { gap: 24px; }
  .hero-stat .num { font-size: 1.8rem; }
  .video-grid { grid-template-columns: 1fr; }
  .community-grid { grid-template-columns: 1fr; }
  .review-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
  .footer-stats { flex-wrap: wrap; gap: 24px; }
  .section { padding: 60px 0; }
  .section-title h2 { font-size: 1.8rem; }
}

@media (max-width: 480px) {
  .hero-content h1 { font-size: 1.6rem; }
  .hero-content p { font-size: 1rem; }
  .hero-stats { flex-direction: column; gap: 16px; }
  .feature-grid { grid-template-columns: 1fr; }
  .expert-grid { grid-template-columns: 1fr; }
  .join-steps { grid-template-columns: 1fr; }
  .container { padding: 0 16px; }
  .search-box input { padding: 14px 50px 14px 18px; }
}