/* roulang page: index */
:root {
      --primary-purple: #B620E0;
      --primary-magenta: #FF007F;
      --accent-cyan: #00F0FF;
      --bg-deep: #0A0E17;
      --bg-card: #131A2B;
      --text-white: #FFFFFF;
      --text-gray: #B0B8C8;
      --text-muted: #6B7280;
      --border-glow: rgba(0, 240, 255, 0.25);
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-data: 16px;
      --shadow-card: 0 4px 24px rgba(0,0,0,0.5);
    }

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

    body {
      font-family: 'Inter', 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
      background-color: var(--bg-deep);
      color: var(--text-white);
      line-height: 1.75;
      -webkit-font-smoothing: antialiased;
    }

    h1, h2, h3, h4 {
      font-family: 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
      font-weight: 700;
      letter-spacing: -0.02em;
    }

    h1 {
      font-size: clamp(2.5rem, 7vw, 3.25rem);
      font-weight: 800;
      line-height: 1.2;
    }

    h2 {
      font-size: clamp(1.8rem, 5vw, 2.5rem);
      font-weight: 700;
    }

    h3 {
      font-size: clamp(1.3rem, 3vw, 1.7rem);
      font-weight: 600;
    }

    p, li {
      color: var(--text-gray);
      font-size: 1rem;
    }

    .container {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 1.5rem;
    }

    .section-padding {
      padding: 5rem 0;
    }

    @media (max-width: 768px) {
      .section-padding {
        padding: 3.5rem 0;
      }
    }

    /* 导航 */
    .desktop-nav {
      background: rgba(10, 14, 23, 0.92);
      backdrop-filter: blur(12px);
      border-bottom: 1px solid rgba(0, 240, 255, 0.3);
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 50;
    }

    .nav-link {
      color: var(--text-gray);
      text-decoration: none;
      font-weight: 500;
      transition: color 0.2s, border-bottom 0.2s;
      border-bottom: 2px solid transparent;
      padding-bottom: 4px;
    }

    .nav-link:hover, .nav-link.active {
      color: var(--accent-cyan);
      border-bottom-color: var(--accent-cyan);
    }

    .mobile-bottom-nav {
      background: #0A0D14;
      border-top: 1px solid #1E2530;
      backdrop-filter: blur(10px);
      display: none;
      position: fixed;
      bottom: 0;
      left: 0;
      width: 100%;
      z-index: 55;
      padding: 0.5rem 1rem;
    }

    @media (max-width: 768px) {
      .mobile-bottom-nav {
        display: flex;
        justify-content: space-around;
        align-items: center;
      }
      .desktop-menu-items {
        display: none;
      }
      .mobile-menu-btn {
        display: block;
      }
    }

    @media (min-width: 769px) {
      .mobile-menu-btn {
        display: none;
      }
      .mobile-bottom-nav {
        display: none;
      }
    }

    .tab-item {
      color: #6B7280;
      text-decoration: none;
      display: flex;
      flex-direction: column;
      align-items: center;
      font-size: 0.7rem;
      font-weight: 500;
      transition: color 0.2s;
    }
    .tab-item i {
      font-size: 1.3rem;
      margin-bottom: 2px;
    }
    .tab-item.active {
      color: var(--accent-cyan);
    }

    /* 按钮 */
    .btn-primary {
      background: linear-gradient(135deg, var(--primary-purple), var(--primary-magenta));
      color: white;
      font-weight: 600;
      padding: 0.85rem 2rem;
      border-radius: var(--radius-btn);
      border: none;
      cursor: pointer;
      transition: all 0.25s;
      box-shadow: 0 4px 15px rgba(182, 32, 224, 0.4);
      display: inline-block;
      text-decoration: none;
      letter-spacing: 0.5px;
    }

    .btn-primary:hover {
      filter: brightness(1.15);
      box-shadow: 0 0 25px rgba(255, 0, 127, 0.6);
      transform: translateY(-1px);
    }

    .btn-ghost {
      background: transparent;
      border: 2px solid var(--accent-cyan);
      color: var(--accent-cyan);
      font-weight: 600;
      padding: 0.8rem 2rem;
      border-radius: var(--radius-btn);
      cursor: pointer;
      transition: all 0.25s;
      display: inline-block;
      text-decoration: none;
      letter-spacing: 0.5px;
    }

    .btn-ghost:hover {
      background: rgba(0, 240, 255, 0.08);
      box-shadow: 0 0 18px rgba(0, 240, 255, 0.3);
    }

    /* 卡片 */
    .card-dark {
      background: var(--bg-card);
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      border: 1px solid transparent;
      transition: all 0.3s ease;
    }

    .card-dark:hover {
      border-color: var(--accent-cyan);
      box-shadow: 0 8px 30px rgba(0, 240, 255, 0.2);
      transform: translateY(-4px);
    }

    .neon-border-hover {
      transition: border 0.3s, box-shadow 0.3s;
    }

    /* 数据数字 */
    .stat-number {
      font-family: 'DIN Alternate', 'Inter', 'PingFang SC', sans-serif;
      font-weight: 800;
      color: var(--accent-cyan);
      font-size: 2.8rem;
      line-height: 1.2;
    }

    /* FAQ */
    .faq-item {
      border-bottom: 1px solid #1F2A3A;
      padding: 1.3rem 0;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
      font-weight: 600;
      color: white;
      font-size: 1.15rem;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.35s ease;
      color: var(--text-gray);
      padding-left: 1rem;
      border-left: 3px solid transparent;
    }
    .faq-item.open .faq-answer {
      max-height: 200px;
      border-left-color: var(--accent-cyan);
      margin-top: 0.8rem;
    }
    .faq-item.open .faq-question {
      color: var(--accent-cyan);
    }

    /* 图片来源 */
    .hero-bg {
      background-image: url('/assets/images/backpic/back-1.webp');
      background-size: cover;
      background-position: center;
    }