/* ============================================
   51吃瓜 - 现代极简高端风格主样式表
   Modern Minimal High-end Forum CSS
   ============================================ */

/* --- CSS Variables --- */
:root {
  --primary: #1a2744;
  --primary-light: #243460;
  --accent: #c9a84c;
  --accent-light: #e8c96a;
  --text-main: #1a1a2e;
  --text-sub: #5a6a8a;
  --text-muted: #9aa5b8;
  --bg-white: #ffffff;
  --bg-light: #f8f9fc;
  --bg-card: #ffffff;
  --border: #e8ecf4;
  --border-light: #f0f3fa;
  --shadow-sm: 0 2px 12px rgba(26,39,68,0.06);
  --shadow-md: 0 8px 32px rgba(26,39,68,0.10);
  --shadow-lg: 0 20px 60px rgba(26,39,68,0.14);
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 24px;
  --transition: all 0.3s cubic-bezier(0.4,0,0.2,1);
  --font-main: 'PingFang SC','Microsoft YaHei','Noto Sans SC',sans-serif;
}

/* --- Reset & Base --- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: var(--font-main);
  color: var(--text-main);
  background: var(--bg-white);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; height: auto; display: block; }
a { text-decoration: none; color: inherit; transition: var(--transition); }
ul, ol { list-style: none; }
button { cursor: pointer; border: none; background: none; font-family: inherit; }

/* --- Typography --- */
h1,h2,h3,h4,h5,h6 { line-height: 1.3; font-weight: 700; color: var(--primary); }
h1 { font-size: clamp(2rem, 5vw, 3.5rem); }
h2 { font-size: clamp(1.5rem, 3vw, 2.4rem); }
h3 { font-size: clamp(1.1rem, 2vw, 1.5rem); }
h4 { font-size: 1.1rem; }
p { color: var(--text-sub); }

/* --- Layout --- */
.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; }
.section { padding: 80px 0; }
.section-sm { padding: 50px 0; }
.section-title { text-align: center; margin-bottom: 56px; }
.section-title h2 { margin-bottom: 14px; }
.section-title p { font-size: 1.05rem; color: var(--text-sub); max-width: 560px; margin: 0 auto; }
.section-title .title-line {
  width: 48px; height: 3px;
  background: linear-gradient(90deg, var(--accent), var(--accent-light));
  margin: 16px auto 0;
  border-radius: 2px;
}

/* --- Header / Navigation --- */
.site-header {
  position: sticky; top: 0; z-index: 1000;
  background: rgba(255,255,255,0.96);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-light);
  transition: var(--transition);
}
.site-header.scrolled { box-shadow: var(--shadow-sm); }
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  height: 68px; gap: 32px;
}
.logo { display: flex; align-items: center; gap: 10px; flex-shrink: 0; }
.logo-icon {
  width: 38px; height: 38px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  color: #fff; font-size: 1.1rem; font-weight: 900;
}
.logo-text { font-size: 1.25rem; font-weight: 800; color: var(--primary); letter-spacing: -0.02em; }
.logo-text span { color: var(--accent); }

.main-nav { display: flex; align-items: center; gap: 4px; }
.main-nav a {
  padding: 7px 16px; border-radius: var(--radius-sm);
  font-size: 0.92rem; font-weight: 500; color: var(--text-sub);
  transition: var(--transition);
}
.main-nav a:hover, .main-nav a.active {
  color: var(--primary); background: var(--bg-light);
}
.header-cta {
  padding: 9px 22px; border-radius: var(--radius-sm);
  background: var(--primary); color: #fff !important;
  font-size: 0.88rem; font-weight: 600;
  transition: var(--transition);
}
.header-cta:hover { background: var(--primary-light); transform: translateY(-1px); box-shadow: var(--shadow-sm); }

/* --- Search Bar --- */
.search-bar-wrap {
  background: var(--bg-light);
  border-bottom: 1px solid var(--border-light);
  padding: 12px 0;
}
.search-bar-inner {
  display: flex; align-items: center; gap: 12px;
  max-width: 680px; margin: 0 auto; padding: 0 24px;
}
.search-input-wrap {
  flex: 1; position: relative;
}
.search-input-wrap input {
  width: 100%; padding: 11px 44px 11px 18px;
  border: 1.5px solid var(--border); border-radius: 50px;
  font-size: 0.93rem; font-family: var(--font-main);
  background: var(--bg-white); color: var(--text-main);
  outline: none; transition: var(--transition);
}
.search-input-wrap input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(201,168,76,0.12); }
.search-input-wrap input::placeholder { color: var(--text-muted); }
.search-btn {
  position: absolute; right: 12px; top: 50%; transform: translateY(-50%);
  color: var(--text-muted); font-size: 1rem; transition: var(--transition);
}
.search-btn:hover { color: var(--accent); }

/* --- Hero Banner --- */
.hero {
  position: relative; overflow: hidden;
  min-height: 560px; display: flex; align-items: center;
  background: linear-gradient(135deg, var(--primary) 0%, #243460 60%, #1a3a6e 100%);
}
.hero-bg {
  position: absolute; inset: 0;
  background-image: url('../images/hero-banner.jpg');
  background-size: cover; background-position: center;
  opacity: 0.18; mix-blend-mode: luminosity;
}
.hero-overlay {
  position: absolute; inset: 0;
  background: linear-gradient(135deg, rgba(26,39,68,0.92) 0%, rgba(26,39,68,0.7) 100%);
}
.hero-content {
  position: relative; z-index: 2;
  max-width: 700px; padding: 80px 0;
}
.hero-badge {
  display: inline-flex; align-items: center; gap: 8px;
  background: rgba(201,168,76,0.15); border: 1px solid rgba(201,168,76,0.3);
  color: var(--accent-light); font-size: 0.82rem; font-weight: 600;
  padding: 6px 16px; border-radius: 50px; margin-bottom: 24px;
  letter-spacing: 0.05em;
}
.hero-badge::before { content: ''; width: 6px; height: 6px; border-radius: 50%; background: var(--accent); animation: pulse 2s infinite; }
.hero h1 { color: #fff; margin-bottom: 20px; }
.hero h1 span { color: var(--accent-light); }
.hero-desc { font-size: 1.1rem; color: rgba(255,255,255,0.75); margin-bottom: 36px; max-width: 520px; }
.hero-actions { display: flex; gap: 14px; flex-wrap: wrap; }
.btn-primary {
  padding: 14px 32px; border-radius: var(--radius-sm);
  background: linear-gradient(135deg, var(--accent), var(--accent-light));
  color: var(--primary); font-weight: 700; font-size: 0.95rem;
  transition: var(--transition); display: inline-flex; align-items: center; gap: 8px;
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(201,168,76,0.4); }
.btn-outline {
  padding: 14px 32px; border-radius: var(--radius-sm);
  border: 1.5px solid rgba(255,255,255,0.3); color: #fff;
  font-weight: 600; font-size: 0.95rem;
  transition: var(--transition); display: inline-flex; align-items: center; gap: 8px;
}
.btn-outline:hover { background: rgba(255,255,255,0.1); border-color: rgba(255,255,255,0.6); }
.hero-stats {
  display: flex; gap: 40px; margin-top: 48px;
  padding-top: 36px; border-top: 1px solid rgba(255,255,255,0.12);
}
.hero-stat-num { font-size: 1.8rem; font-weight: 800; color: var(--accent-light); }
.hero-stat-label { font-size: 0.82rem; color: rgba(255,255,255,0.55); margin-top: 2px; }

/* --- Video Cards --- */
.video-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px,1fr)); gap: 24px; }
.video-card {
  background: var(--bg-card); border-radius: var(--radius-md);
  overflow: hidden; box-shadow: var(--shadow-sm);
  border: 1px solid var(--border-light);
  transition: var(--transition); cursor: pointer;
}
.video-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); }
.video-thumb {
  position: relative; overflow: hidden;
  aspect-ratio: 16/9; background: var(--bg-light);
}
.video-thumb img { width: 100%; height: 100%; object-fit: cover; transition: transform 0.5s ease; }
.video-card:hover .video-thumb img { transform: scale(1.05); }
.video-play-btn {
  position: absolute; inset: 0; display: flex; align-items: center; justify-content: center;
  background: rgba(26,39,68,0.3); opacity: 0; transition: var(--transition);
}
.video-card:hover .video-play-btn { opacity: 1; }
.play-circle {
  width: 56px; height: 56px; border-radius: 50%;
  background: rgba(255,255,255,0.95); display: flex; align-items: center; justify-content: center;
  transform: scale(0.85); transition: var(--transition);
  box-shadow: 0 4px 20px rgba(0,0,0,0.3);
}
.video-card:hover .play-circle { transform: scale(1); }
.play-icon { width: 0; height: 0; border-style: solid; border-width: 10px 0 10px 18px; border-color: transparent transparent transparent var(--primary); margin-left: 3px; }
.video-badge {
  position: absolute; top: 10px; left: 10px;
  background: var(--accent); color: var(--primary);
  font-size: 0.72rem; font-weight: 700; padding: 3px 10px; border-radius: 50px;
  letter-spacing: 0.04em;
}
.video-duration {
  position: absolute; bottom: 10px; right: 10px;
  background: rgba(0,0,0,0.7); color: #fff;
  font-size: 0.75rem; padding: 3px 8px; border-radius: 4px;
}
.video-info { padding: 16px; }
.video-title { font-size: 0.95rem; font-weight: 600; color: var(--text-main); margin-bottom: 10px; line-height: 1.5; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
.video-meta { display: flex; align-items: center; gap: 14px; font-size: 0.8rem; color: var(--text-muted); }
.video-meta span { display: flex; align-items: center; gap: 4px; }

/* --- Topic Cards --- */
.topic-list { display: flex; flex-direction: column; gap: 1px; }
.topic-item {
  display: flex; align-items: center; gap: 18px;
  padding: 18px 20px; background: var(--bg-card);
  border-radius: var(--radius-sm); border: 1px solid var(--border-light);
  transition: var(--transition); margin-bottom: 8px;
}
.topic-item:hover { box-shadow: var(--shadow-sm); border-color: var(--border); transform: translateX(4px); }
.topic-rank { width: 28px; height: 28px; border-radius: 8px; display: flex; align-items: center; justify-content: center; font-size: 0.8rem; font-weight: 700; flex-shrink: 0; }
.topic-rank.top1 { background: linear-gradient(135deg, #c9a84c, #e8c96a); color: var(--primary); }
.topic-rank.top2 { background: #e8ecf4; color: var(--text-sub); }
.topic-rank.top3 { background: #f0ece8; color: #a0856a; }
.topic-rank.other { background: var(--bg-light); color: var(--text-muted); }
.topic-content { flex: 1; min-width: 0; }
.topic-title-link { font-size: 0.93rem; font-weight: 600; color: var(--text-main); display: block; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.topic-title-link:hover { color: var(--accent); }
.topic-tags { display: flex; gap: 6px; margin-top: 4px; }
.tag { font-size: 0.72rem; padding: 2px 8px; border-radius: 4px; background: var(--bg-light); color: var(--text-muted); }
.tag.hot { background: rgba(201,168,76,0.1); color: var(--accent); }
.tag.video { background: rgba(26,39,68,0.07); color: var(--primary); }
.topic-stats { display: flex; gap: 16px; font-size: 0.78rem; color: var(--text-muted); flex-shrink: 0; }
.topic-stats span { display: flex; align-items: center; gap: 3px; }

/* --- Category Grid --- */
.category-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px,1fr)); gap: 20px; }
.category-card {
  padding: 28px 24px; border-radius: var(--radius-md);
  background: var(--bg-card); border: 1px solid var(--border-light);
  transition: var(--transition); text-align: center;
}
.category-card:hover { box-shadow: var(--shadow-md); transform: translateY(-4px); border-color: var(--accent); }
.category-icon {
  width: 56px; height: 56px; border-radius: 16px; margin: 0 auto 16px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.5rem;
  background: linear-gradient(135deg, rgba(26,39,68,0.06), rgba(201,168,76,0.08));
}
.category-name { font-size: 1rem; font-weight: 700; color: var(--primary); margin-bottom: 6px; }
.category-desc { font-size: 0.82rem; color: var(--text-muted); }
.category-count { font-size: 0.78rem; color: var(--accent); font-weight: 600; margin-top: 10px; }

/* --- Stats Section --- */
.stats-section { background: var(--primary); }
.stats-grid { display: grid; grid-template-columns: repeat(4,1fr); gap: 0; }
.stat-item { padding: 48px 24px; text-align: center; border-right: 1px solid rgba(255,255,255,0.08); }
.stat-item:last-child { border-right: none; }
.stat-num { font-size: 2.8rem; font-weight: 800; color: var(--accent-light); line-height: 1; }
.stat-unit { font-size: 1rem; color: var(--accent); margin-left: 2px; }
.stat-label { font-size: 0.85rem; color: rgba(255,255,255,0.55); margin-top: 8px; }

/* --- Reviews --- */
.reviews-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px,1fr)); gap: 24px; }
.review-card {
  padding: 28px; border-radius: var(--radius-md);
  background: var(--bg-card); border: 1px solid var(--border-light);
  box-shadow: var(--shadow-sm); transition: var(--transition);
}
.review-card:hover { box-shadow: var(--shadow-md); transform: translateY(-2px); }
.review-stars { color: var(--accent); font-size: 0.9rem; margin-bottom: 12px; letter-spacing: 2px; }
.review-text { font-size: 0.9rem; color: var(--text-sub); line-height: 1.7; margin-bottom: 18px; font-style: italic; }
.review-author { display: flex; align-items: center; gap: 12px; }
.review-avatar { width: 40px; height: 40px; border-radius: 50%; object-fit: cover; }
.review-name { font-size: 0.88rem; font-weight: 600; color: var(--primary); }
.review-role { font-size: 0.76rem; color: var(--text-muted); }

/* --- FAQ --- */
.faq-list { max-width: 760px; margin: 0 auto; }
.faq-item {
  border: 1px solid var(--border); border-radius: var(--radius-sm);
  margin-bottom: 10px; overflow: hidden; transition: var(--transition);
}
.faq-item.open { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(201,168,76,0.08); }
.faq-question {
  display: flex; align-items: center; justify-content: space-between;
  padding: 18px 22px; cursor: pointer; user-select: none;
  font-size: 0.95rem; font-weight: 600; color: var(--primary);
  transition: var(--transition);
}
.faq-question:hover { background: var(--bg-light); }
.faq-icon { width: 22px; height: 22px; border-radius: 50%; background: var(--bg-light); display: flex; align-items: center; justify-content: center; flex-shrink: 0; transition: var(--transition); font-size: 0.8rem; color: var(--text-muted); }
.faq-item.open .faq-icon { background: var(--accent); color: var(--primary); transform: rotate(45deg); }
.faq-answer { display: none; padding: 0 22px 18px; font-size: 0.88rem; color: var(--text-sub); line-height: 1.8; }
.faq-item.open .faq-answer { display: block; }

/* --- CTA Section --- */
.cta-section {
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  text-align: center; padding: 80px 0;
}
.cta-section h2 { color: #fff; margin-bottom: 14px; }
.cta-section p { color: rgba(255,255,255,0.7); margin-bottom: 36px; font-size: 1.05rem; }

/* --- Footer --- */
.site-footer {
  background: #0f1829;
  color: rgba(255,255,255,0.6);
  padding: 60px 0 0;
}
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 48px; margin-bottom: 48px; }
.footer-brand .logo-text { color: #fff; font-size: 1.3rem; }
.footer-brand p { font-size: 0.85rem; color: rgba(255,255,255,0.45); margin-top: 14px; line-height: 1.8; }
.footer-col h4 { color: rgba(255,255,255,0.85); font-size: 0.9rem; font-weight: 700; margin-bottom: 16px; letter-spacing: 0.04em; }
.footer-col a { display: block; font-size: 0.83rem; color: rgba(255,255,255,0.45); margin-bottom: 10px; transition: var(--transition); }
.footer-col a:hover { color: var(--accent-light); }
.footer-social { display: flex; gap: 10px; margin-top: 18px; }
.social-btn { width: 36px; height: 36px; border-radius: 8px; background: rgba(255,255,255,0.07); display: flex; align-items: center; justify-content: center; font-size: 0.85rem; color: rgba(255,255,255,0.5); transition: var(--transition); }
.social-btn:hover { background: var(--accent); color: var(--primary); }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.07);
  padding: 20px 0; display: flex; align-items: center; justify-content: space-between;
  font-size: 0.8rem; color: rgba(255,255,255,0.3);
}
.footer-bottom a { color: rgba(255,255,255,0.4); }
.footer-bottom a:hover { color: var(--accent-light); }

/* --- Breadcrumb --- */
.breadcrumb { padding: 14px 0; font-size: 0.82rem; color: var(--text-muted); }
.breadcrumb a { color: var(--text-muted); }
.breadcrumb a:hover { color: var(--accent); }
.breadcrumb span { margin: 0 6px; }

/* --- Inner Page Header --- */
.page-header {
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  padding: 56px 0; text-align: center;
}
.page-header h1 { color: #fff; margin-bottom: 10px; }
.page-header p { color: rgba(255,255,255,0.65); font-size: 1rem; }

/* --- Animations --- */
@keyframes pulse { 0%,100%{opacity:1;transform:scale(1)} 50%{opacity:0.6;transform:scale(1.3)} }
@keyframes fadeInUp { from{opacity:0;transform:translateY(24px)} to{opacity:1;transform:translateY(0)} }
.animate-in { animation: fadeInUp 0.6s ease forwards; }

/* --- Mobile Hamburger --- */
.hamburger { display: none; flex-direction: column; gap: 5px; cursor: pointer; padding: 4px; }
.hamburger span { width: 22px; height: 2px; background: var(--primary); border-radius: 2px; transition: var(--transition); }

/* --- Responsive --- */
@media (max-width: 1024px) {
  .stats-grid { grid-template-columns: repeat(2,1fr); }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 32px; }
}
@media (max-width: 768px) {
  .section { padding: 56px 0; }
  .main-nav { display: none; position: absolute; top: 68px; left: 0; right: 0; background: #fff; flex-direction: column; padding: 16px; border-bottom: 1px solid var(--border); box-shadow: var(--shadow-md); }
  .main-nav.open { display: flex; }
  .main-nav a { padding: 12px 16px; border-radius: var(--radius-sm); }
  .hamburger { display: flex; }
  .header-cta { display: none; }
  .hero-stats { gap: 24px; flex-wrap: wrap; }
  .hero-stat-num { font-size: 1.4rem; }
  .stats-grid { grid-template-columns: repeat(2,1fr); }
  .footer-grid { grid-template-columns: 1fr; gap: 28px; }
  .footer-bottom { flex-direction: column; gap: 8px; text-align: center; }
  .video-grid { grid-template-columns: 1fr; }
  .category-grid { grid-template-columns: repeat(2,1fr); }
  .reviews-grid { grid-template-columns: 1fr; }
}
@media (max-width: 480px) {
  .container { padding: 0 16px; }
  .hero-actions { flex-direction: column; }
  .btn-primary, .btn-outline { justify-content: center; }
  .category-grid { grid-template-columns: 1fr 1fr; }
  .stats-grid { grid-template-columns: 1fr 1fr; }
}