/* roulang page: index */
:root {
      --deep-black: #0A0E27;
      --card-bg: #131833;
      --cyber-cyan: #00F0FF;
      --competition-red: #FF4655;
      --white: #ffffff;
      --text-light: #B0B8D1;
      --text-muted: #7B8299;
      --border-dim: rgba(0,240,255,0.18);
      --radius-sm: 8px;
      --radius-md: 12px;
      --radius-btn: 4px;
      --shadow-glow: 0 0 20px rgba(0,240,255,0.25);
      --shadow-card: 0 4px 24px rgba(0,0,0,0.35);
      --font-sans: 'PingFang SC', 'Microsoft YaHei', 'Segoe UI', system-ui, sans-serif;
      --font-mono: 'DIN Alternate', 'Roboto', 'Segoe UI', monospace;
      --section-padding: 100px 0;
      --container-max: 1280px;
      --transition-smooth: all 0.25s ease;
    }

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

    body {
      background-color: var(--deep-black);
      color: var(--text-light);
      font-family: var(--font-sans);
      line-height: 1.8;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
      background-image: radial-gradient(circle at 30% 40%, rgba(0,240,255,0.04) 0%, transparent 45%);
    }

    .container {
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 32px;
    }

    img {
      max-width: 100%;
      display: block;
      height: auto;
    }

    a {
      text-decoration: none;
      color: var(--cyber-cyan);
      transition: var(--transition-smooth);
    }

    button, .btn {
      cursor: pointer;
      font-family: var(--font-sans);
      border: none;
      background: none;
    }

    h1, h2, h3, .stat-number {
      color: var(--white);
      font-weight: 700;
    }

    h1 {
      font-size: 56px;
      letter-spacing: -0.5px;
      line-height: 1.2;
      background: linear-gradient(135deg, #ffffff 0%, #e0f2ff 80%);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      background-clip: text;
    }

    h2 {
      font-size: 40px;
      margin-bottom: 16px;
    }

    h3 {
      font-size: 24px;
      font-weight: 600;
      margin-bottom: 12px;
    }

    .section {
      padding: var(--section-padding);
    }

    /* ---------- 导航 ---------- */
    .header {
      position: sticky;
      top: 0;
      z-index: 50;
      background: rgba(10,14,39,0.85);
      backdrop-filter: blur(16px);
      border-bottom: 1px solid rgba(0,240,255,0.12);
      padding: 16px 0;
    }

    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      flex-wrap: nowrap;
    }

    .logo-center {
      order: 2;
      font-weight: 700;
      font-size: 28px;
      letter-spacing: 1px;
      color: var(--white);
      text-shadow: 0 0 8px rgba(0,240,255,0.6);
      font-family: var(--font-mono);
    }

    .nav-left, .nav-right {
      display: flex;
      gap: 36px;
      align-items: center;
    }

    .nav-left {
      order: 1;
    }

    .nav-right {
      order: 3;
    }

    .nav-link {
      color: var(--text-light);
      font-weight: 500;
      font-size: 16px;
      position: relative;
      padding: 4px 0;
    }

    .nav-link::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 0%;
      height: 2px;
      background: var(--cyber-cyan);
      transition: 0.25s ease;
    }

    .nav-link:hover {
      color: var(--white);
    }

    .nav-link:hover::after {
      width: 100%;
    }

    .mobile-menu-toggle {
      display: none;
      background: none;
      border: none;
      color: var(--white);
      font-size: 28px;
    }

    @media (max-width: 1024px) {
      .nav-left, .nav-right {
        gap: 20px;
      }
    }

    @media (max-width: 768px) {
      .nav-left, .nav-right {
        display: none;
      }
      .mobile-menu-toggle {
        display: block;
        order: 3;
      }
      .logo-center {
        order: 2;
      }
      .header .container {
        flex-wrap: wrap;
      }
      .nav-mobile {
        display: none;
        flex-direction: column;
        background: rgba(10,14,39,0.96);
        width: 100%;
        padding: 20px 32px;
        gap: 18px;
      }
      .nav-mobile.active {
        display: flex;
      }
    }

    /* ---------- 按钮 ---------- */
    .btn-primary {
      background: var(--competition-red);
      color: white;
      padding: 14px 34px;
      border-radius: var(--radius-btn);
      font-weight: 700;
      letter-spacing: 0.5px;
      display: inline-block;
      box-shadow: 0 8px 18px rgba(255,70,85,0.4);
      transition: 0.2s;
    }

    .btn-primary:hover {
      background: #ff5a6a;
      box-shadow: 0 10px 28px rgba(255,70,85,0.6);
      transform: translateY(-2px);
    }

    .btn-ghost {
      border: 1px solid var(--cyber-cyan);
      color: var(--cyber-cyan);
      padding: 12px 30px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      background: transparent;
    }

    .btn-ghost:hover {
      background: rgba(0,240,255,0.08);
      box-shadow: 0 0 15px rgba(0,240,255,0.35);
    }

    /* ---------- Hero ---------- */
    .hero {
      padding: 120px 0 100px;
      background-image: url('/assets/images/backpic/back-1.webp');
      background-size: cover;
      background-position: center;
      position: relative;
    }

    .hero::before {
      content: '';
      position: absolute;
      inset: 0;
      background: linear-gradient(90deg, #0A0E27 5%, rgba(10,14,39,0.7) 60%, transparent);
    }

    .hero-content {
      position: relative;
      z-index: 2;
      max-width: 700px;
    }

    .hero h1 {
      margin-bottom: 24px;
      font-size: 56px;
    }

    .hero .sub {
      font-size: 20px;
      color: #ccd6f0;
      margin-bottom: 36px;
    }

    /* ---------- 卡片通用 ---------- */
    .card {
      background: rgba(19,24,51,0.8);
      backdrop-filter: blur(8px);
      border: 1px solid var(--border-dim);
      border-radius: var(--radius-md);
      padding: 28px;
      transition: var(--transition-smooth);
    }

    .card:hover {
      border-color: var(--cyber-cyan);
      box-shadow: 0 0 20px rgba(0,240,255,0.25);
      transform: translateY(-4px);
    }

    .grid-3, .grid-2 {
      display: grid;
      gap: 30px;
    }

    .grid-3 { grid-template-columns: repeat(3,1fr); }
    .grid-2 { grid-template-columns: repeat(2,1fr); }

    /* ---------- 数据数字 ---------- */
    .stat-number {
      font-family: var(--font-mono);
      font-size: 48px;
      color: var(--cyber-cyan);
      text-shadow: 0 0 12px rgba(0,240,255,0.6);
    }

    .data-grid {
      display: flex;
      justify-content: space-around;
      flex-wrap: wrap;
      text-align: center;
      gap: 30px;
    }

    /* ---------- FAQ ---------- */
    .faq-item {
      border-bottom: 1px solid rgba(0,240,255,0.2);
      padding: 22px 0;
      cursor: pointer;
    }

    .faq-question {
      display: flex;
      justify-content: space-between;
      font-weight: 600;
      color: white;
      font-size: 18px;
    }

    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease;
      color: var(--text-light);
      margin-top: 8px;
    }

    .faq-item.active .faq-answer {
      max-height: 200px;
    }

    /* ---------- 页脚 ---------- */
    .footer {
      background: #070b1c;
      padding: 60px 0 30px;
      color: var(--text-muted);
      border-top: 1px solid rgba(0,240,255,0.2);
    }

    .footer-grid {
      display: flex;
      justify-content: space-between;
      flex-wrap: wrap;
      gap: 40px;
    }

    @media (max-width: 768px) {
      h1 { font-size: 36px; }
      h2 { font-size: 28px; }
      .grid-3, .grid-2 { grid-template-columns: 1fr; }
      .hero { padding: 80px 0; }
      .section { padding: 70px 0; }
      .data-grid { flex-direction: column; align-items: center; }
    }