/* roulang page: index */
:root {
      --bg-deep: #0A0F1F;
      --bg-card: #1A2035;
      --primary-cyan: #00E5FF;
      --accent-red: #FF3D00;
      --text-white: #FFFFFF;
      --text-steel: #B0C4DE;
      --glass-bg: rgba(21, 30, 50, 0.65);
      --glass-border: rgba(0, 229, 255, 0.18);
      --card-radius: 16px;
      --button-radius: 8px;
      --gap-section: 6rem;
      --font-tech: 'Orbitron', 'Rajdhani', 'Noto Sans SC', sans-serif;
      --transition-smooth: all 0.25s ease;
    }

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

    body {
      background-color: var(--bg-deep);
      color: var(--text-white);
      font-family: 'Inter', 'Noto Sans SC', sans-serif;
      line-height: 1.7;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
      scroll-behavior: smooth;
    }

    .container {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 2rem;
    }

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

    a {
      text-decoration: none;
      color: inherit;
    }

    /* 导航律动 */
    .main-nav {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background: rgba(10, 15, 31, 0.75);
      backdrop-filter: blur(20px);
      -webkit-backdrop-filter: blur(20px);
      border-bottom: 1px solid rgba(0, 229, 255, 0.1);
      z-index: 1000;
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 0 2.5rem;
      height: 72px;
    }

    .logo {
      font-family: var(--font-tech);
      font-size: 1.9rem;
      font-weight: 700;
      letter-spacing: 1px;
      color: var(--primary-cyan);
      display: flex;
      align-items: center;
      gap: 0.5rem;
      text-shadow: 0 0 12px rgba(0, 229, 255, 0.6);
    }

    .logo::before {
      content: "";
      display: inline-block;
      width: 14px;
      height: 14px;
      background: var(--primary-cyan);
      border-radius: 50%;
      box-shadow: 0 0 15px var(--primary-cyan);
      margin-right: 4px;
    }

    .nav-links {
      display: flex;
      gap: 2.5rem;
      align-items: center;
    }

    .nav-links a {
      font-weight: 500;
      color: var(--text-steel);
      transition: var(--transition-smooth);
      position: relative;
      padding: 0.25rem 0;
      letter-spacing: 0.3px;
    }

    .nav-links a::after {
      content: "";
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--primary-cyan);
      box-shadow: 0 0 8px var(--primary-cyan);
      transition: width 0.3s ease;
    }

    .nav-links a:hover {
      color: var(--primary-cyan);
    }

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

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: transparent;
      border: none;
    }

    .hamburger span {
      width: 26px;
      height: 2px;
      background: var(--primary-cyan);
      transition: 0.3s;
    }

    @media (max-width: 768px) {
      .nav-links {
        position: fixed;
        top: 72px;
        left: 0;
        width: 100%;
        background: rgba(10, 15, 31, 0.96);
        backdrop-filter: blur(20px);
        flex-direction: column;
        align-items: center;
        gap: 2rem;
        padding: 2.5rem 1.5rem;
        transform: translateY(-150%);
        transition: transform 0.4s ease-in-out;
        border-bottom: 1px solid rgba(0,229,255,0.25);
      }
      .nav-links.active {
        transform: translateY(0);
      }
      .hamburger {
        display: flex;
        background: none;
        border: none;
      }
    }

    /* 块级区域通用 */
    section {
      padding: var(--gap-section) 0;
    }

    h2 {
      font-size: 2.4rem;
      font-weight: 600;
      margin-bottom: 2.2rem;
      letter-spacing: -0.5px;
      background: linear-gradient(to right, #FFF, #B0C4DE);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      position: relative;
      display: inline-block;
    }

    .glass-card {
      background: rgba(26, 32, 53, 0.55);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      border: 1px solid rgba(0, 229, 255, 0.25);
      border-radius: var(--card-radius);
      box-shadow: 0 10px 25px -8px rgba(0,0,0,0.5);
      transition: var(--transition-smooth);
    }

    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      border-radius: var(--button-radius);
      font-weight: 600;
      letter-spacing: 0.4px;
      padding: 0.85rem 2rem;
      font-size: 1rem;
      cursor: pointer;
      transition: var(--transition-smooth);
    }

    .btn-primary {
      background: var(--accent-red);
      color: white;
      box-shadow: 0 4px 14px rgba(255, 61, 0, 0.5);
      border: none;
    }
    .btn-primary:hover {
      box-shadow: 0 8px 22px rgba(255, 61, 0, 0.75);
      transform: translateY(-2px);
    }

    .btn-glass {
      background: transparent;
      border: 1px solid var(--primary-cyan);
      color: var(--primary-cyan);
      box-shadow: 0 0 10px rgba(0,229,255,0.2);
    }
    .btn-glass:hover {
      box-shadow: 0 0 22px rgba(0,229,255,0.7);
      background: rgba(0,229,255,0.08);
      transform: translateY(-2px);
    }