/* roulang page: index */
:root {
      --primary: #F04E23;
      --primary-dark: #E03C1A;
      --secondary: #1B2A3B;
      --bg: #F9FAFB;
      --card-bg: #FFFFFF;
      --text-main: #1F2937;
      --text-muted: #6B7280;
      --text-white: #FFFFFF;
      --success: #10B981;
      --border-light: #E5E7EB;
      --shadow-card: 0 1px 3px rgba(0,0,0,0.06), 0 4px 12px rgba(0,0,0,0.04);
      --shadow-card-hover: 0 8px 24px rgba(0,0,0,0.10);
      --shadow-nav: 0 2px 12px rgba(0,0,0,0.06);
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-input: 6px;
      --transition: 0.25s ease;
      --section-gap: 100px;
      --content-width: 1200px;
      --grid-gap: 24px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    body {
      font-family: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", "Inter", "Poppins", sans-serif;
      background-color: var(--bg);
      color: var(--text-main);
      line-height: 1.4;
      -webkit-font-smoothing: antialiased;
      scroll-behavior: smooth;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
    }
    ul {
      list-style: none;
    }
    button, .btn {
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      font-weight: 600;
      border-radius: var(--radius-btn);
      transition: all var(--transition);
      font-size: 16px;
      white-space: nowrap;
      border: none;
      outline: none;
    }
    .container {
      max-width: var(--content-width);
      margin: 0 auto;
      padding: 0 24px;
      width: 100%;
    }
    /* 导航 */
    .navbar {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background: rgba(255,255,255,0.96);
      backdrop-filter: blur(8px);
      z-index: 1000;
      transition: box-shadow var(--transition);
      height: 72px;
      display: flex;
      align-items: center;
    }
    .navbar.shadow {
      box-shadow: var(--shadow-nav);
    }
    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
    }
    .logo {
      font-size: 22px;
      font-weight: 800;
      color: var(--primary);
      letter-spacing: -0.3px;
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 32px;
    }
    .nav-links a {
      font-weight: 500;
      color: var(--text-main);
      position: relative;
      padding: 8px 0;
      transition: color var(--transition);
    }
    .nav-links a:hover,
    .nav-links a.active {
      color: var(--primary);
    }
    .nav-links a.active::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 100%;
      height: 2px;
      background: var(--primary);
      border-radius: 1px;
    }
    .btn-primary {
      background: var(--primary);
      color: var(--text-white);
      padding: 12px 28px;
      border-radius: var(--radius-btn);
    }
    .btn-primary:hover {
      background: var(--primary-dark);
      box-shadow: 0 0 0 3px rgba(240,78,35,0.3);
    }
    .btn-outline {
      background: transparent;
      border: 2px solid var(--secondary);
      color: var(--secondary);
      padding: 12px 28px;
    }
    .btn-outline:hover {
      background: rgba(27,42,59,0.05);
    }
    .btn-outline-white {
      border-color: var(--text-white);
      color: var(--text-white);
    }
    .btn-outline-white:hover {
      background: rgba(255,255,255,0.1);
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      background: none;
      border: none;
      width: 28px;
      height: 18px;
      cursor: pointer;
    }
    .hamburger span {
      display: block;
      height: 2px;
      background: var(--secondary);
      border-radius: 2px;
      transition: var(--transition);
    }
    /* Hero */
    .hero {
      padding: 140px 0 80px;
      background: linear-gradient(135deg, rgba(27,42,59,0.7) 0%, rgba(27,42,59,0.2) 100%), 
                  url('/assets/images/backpic/back-1.webp') center/cover no-repeat;
      color: var(--text-white);
    }
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 60px;
      align-items: center;
    }
    .hero h1 {
      font-size: 48px;
      line-height: 56px;
      font-weight: 800;
      letter-spacing: -0.5px;
      color: var(--text-white);
      margin-bottom: 16px;
    }
    .hero .subtitle {
      font-size: 20px;
      font-weight: 400;
      color: rgba(255,255,255,0.9);
      margin-bottom: 32px;
    }
    .hero-actions {
      display: flex;
      gap: 20px;
      flex-wrap: wrap;
    }
    .hero-visual {
      background: url('/assets/images/coverpic/cover-1.webp') center/cover no-repeat;
      border-radius: var(--radius-card);
      min-height: 360px;
      box-shadow: var(--shadow-card);
    }
    /* 通用section */
    .section {
      padding: var(--section-gap) 0;
    }
    .section-title {
      font-size: 36px;
      line-height: 44px;
      font-weight: 700;
      color: var(--secondary);
      text-align: center;
      margin-bottom: 12px;
      position: relative;
    }
    .section-title::after {
      content: '';
      display: block;
      width: 48px;
      height: 4px;
      background: var(--primary);
      margin: 12px auto 0;
      border-radius: 2px;
    }
    .section-sub {
      text-align: center;
      font-size: 18px;
      color: var(--text-muted);
      margin-bottom: 48px;
    }
    .grid-4 {
      display: grid;
      grid-template-columns: repeat(4,1fr);
      gap: var(--grid-gap);
    }
    .grid-3 {
      display: grid;
      grid-template-columns: repeat(3,1fr);
      gap: var(--grid-gap);
    }
    .card {
      background: var(--card-bg);
      border-radius: var(--radius-card);
      padding: 32px;
      box-shadow: var(--shadow-card);
      transition: all var(--transition);
    }
    .card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-card-hover);
    }
    .card-icon {
      font-size: 36px;
      color: var(--primary);
      margin-bottom: 16px;
    }
    .card h3 {
      font-size: 22px;
      font-weight: 600;
      color: var(--secondary);
      margin-bottom: 8px;
    }
    .card p {
      color: var(--text-muted);
      line-height: 1.6;
    }
    .alt-row {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 60px;
      align-items: center;
      margin-bottom: 64px;
    }
    .alt-row:last-child {
      margin-bottom: 0;
    }
    .alt-img {
      background: url('/assets/images/coverpic/cover-2.webp') center/cover no-repeat;
      border-radius: var(--radius-card);
      min-height: 320px;
      box-shadow: var(--shadow-card);
    }
    .tag {
      display: inline-block;
      background: #F3F4F6;
      color: var(--text-muted);
      border-radius: 20px;
      padding: 4px 14px;
      font-size: 13px;
      font-weight: 500;
      margin-right: 8px;
    }
    .dark-bg {
      background: var(--secondary);
      color: var(--text-white);
    }
    .dark-bg .section-title {
      color: var(--text-white);
    }
    .stats-lg {
      font-size: 56px;
      font-weight: 900;
      color: var(--success);
      line-height: 1.1;
    }
    .faq-item {
      background: var(--card-bg);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-card);
      margin-bottom: 12px;
      overflow: hidden;
      transition: border var(--transition);
    }
    .faq-item:hover {
      border-color: var(--primary);
    }
    .faq-q {
      padding: 18px 24px;
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
      color: var(--secondary);
    }
    .faq-a {
      padding: 0 24px 18px;
      color: var(--text-muted);
      display: none;
    }
    .faq-item.open .faq-a {
      display: block;
    }
    .cta-section {
      background: var(--secondary);
      padding: 80px 0;
      text-align: center;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
      padding: 60px 0;
    }
    .footer-bottom {
      border-top: 1px solid var(--border-light);
      padding: 24px 0;
      text-align: center;
      color: var(--text-muted);
    }
    @media (max-width: 1024px) {
      .grid-4 { grid-template-columns: repeat(2,1fr); }
      .grid-3 { grid-template-columns: repeat(2,1fr); }
      .hero h1 { font-size: 38px; line-height: 46px; }
    }
    @media (max-width: 768px) {
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .hero-grid, .alt-row { grid-template-columns: 1fr; }
      .hero-visual, .alt-img { min-height: 240px; }
      .footer-grid { grid-template-columns: 1fr; }
      .section-title { font-size: 28px; }
    }
    @media (max-width: 520px) {
      .grid-4, .grid-3 { grid-template-columns: 1fr; }
      .hero h1 { font-size: 32px; line-height: 40px; }
    }
    .mobile-menu {
      position: fixed; top:0; left:0; width:100%; height:100%;
      background: var(--primary); display: flex; flex-direction: column;
      align-items: center; justify-content: center; gap:28px; z-index: 2000;
      transform: translateX(100%); transition: transform 0.3s ease;
    }
    .mobile-menu.open { transform: translateX(0); }
    .mobile-menu a { color: white; font-size: 22px; font-weight: 600; }