/* roulang page: index */
/* ----- CSS变量与设计令牌 ----- */
    :root {
      --bg-deep: #0D0B1E;
      --bg-card: rgba(30, 27, 46, 0.8);
      --bg-section: #1E1B2E;
      --primary-purple: #8B5CF6;
      --accent-cyan: #00F0FF;
      --neutral-white: #F8F9FA;
      --text-secondary: #9CA3AF;
      --font-sans: -apple-system, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --font-mono: "SF Mono", "JetBrains Mono", "Courier New", monospace;
      --radius: 16px;
      --radius-sm: 8px;
      --transition: 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
      --shadow-deep: 0 8px 32px rgba(0, 0, 0, 0.45);
      --border-light: 1px solid rgba(139, 92, 246, 0.2);
      --max-width: 1280px;
    }

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

    html {
      scroll-behavior: smooth;
      font-size: 16px;
    }

    body {
      background-color: var(--bg-deep);
      color: var(--neutral-white);
      font-family: var(--font-sans);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
      letter-spacing: 0.01em;
    }

    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
      width: 100%;
    }

    /* ----- 导航栏：半透明深色，毛玻璃效果 ----- */
    .site-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 72px;
      background: rgba(13, 11, 30, 0.8);
      backdrop-filter: blur(20px);
      -webkit-backdrop-filter: blur(20px);
      z-index: 1000;
      border-bottom: 1px solid rgba(139, 92, 246, 0.15);
      display: flex;
      align-items: center;
    }

    .header-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
    }

    .logo {
      font-size: 1.6rem;
      font-weight: 700;
      letter-spacing: -0.01em;
      color: var(--neutral-white);
      text-decoration: none;
      display: flex;
      align-items: center;
      gap: 8px;
      white-space: nowrap;
    }
    .logo span {
      color: var(--accent-cyan);
    }

    .nav-menu {
      display: flex;
      gap: 32px;
      align-items: center;
    }

    .nav-link {
      text-decoration: none;
      font-weight: 500;
      color: var(--text-secondary);
      font-size: 0.95rem;
      position: relative;
      padding: 6px 0;
      transition: color var(--transition);
    }

    .nav-link::after {
      content: '';
      position: absolute;
      bottom: -2px;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--accent-cyan);
      transition: width var(--transition);
    }

    .nav-link:hover,
    .nav-link.active {
      color: var(--neutral-white);
    }
    .nav-link:hover::after,
    .nav-link.active::after {
      width: 100%;
    }

    .hamburger {
      display: none;
      flex-direction: column;
      cursor: pointer;
      gap: 6px;
      background: transparent;
      border: none;
      padding: 4px;
      z-index: 1001;
    }
    .hamburger span {
      display: block;
      width: 26px;
      height: 2px;
      background: var(--neutral-white);
      transition: var(--transition);
    }

    /* 移动端菜单 */
    @media (max-width: 768px) {
      .nav-menu {
        position: fixed;
        top: 0;
        right: 0;
        height: 100vh;
        width: 75%;
        background: rgba(13, 11, 30, 0.96);
        backdrop-filter: blur(30px);
        flex-direction: column;
        justify-content: center;
        align-items: flex-start;
        padding: 40px 32px;
        gap: 28px;
        transform: translateX(100%);
        transition: transform 0.35s ease;
      }
      .nav-menu.is-open {
        transform: translateX(0);
      }
      .hamburger {
        display: flex;
      }
      .nav-link {
        font-size: 1.25rem;
      }
    }

    /* 区块通用间距 */
    section {
      padding: 100px 0;
    }
    @media (max-width: 768px) {
      section {
        padding: 70px 0;
      }
    }

    /* 标题层级 */
    h1 {
      font-size: 2.75rem;
      font-weight: 700;
      letter-spacing: -0.02em;
      line-height: 1.2;
    }
    h2 {
      font-size: 2rem;
      font-weight: 700;
      border-left: 4px solid var(--accent-cyan);
      padding-left: 20px;
      margin-bottom: 40px;
      color: #fff;
    }
    h3 {
      font-size: 1.25rem;
      font-weight: 600;
    }
    .text-mono {
      font-family: var(--font-mono);
      font-weight: 500;
      color: var(--accent-cyan);
    }

    /* 卡片系统 */
    .card-glass {
      background: var(--bg-card);
      backdrop-filter: blur(12px);
      border-radius: var(--radius);
      border: var(--border-light);
      box-shadow: var(--shadow-deep);
      transition: transform var(--transition), border-color var(--transition);
    }
    .card-glass:hover {
      transform: translateY(-4px);
      border-color: rgba(0, 240, 255, 0.5);
    }

    /* 按钮体系 */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 12px 28px;
      border-radius: var(--radius-sm);
      font-weight: 600;
      text-decoration: none;
      transition: all var(--transition);
      cursor: pointer;
      border: none;
      font-size: 1rem;
      gap: 8px;
    }
    .btn-primary {
      background: var(--primary-purple);
      color: white;
      box-shadow: 0 4px 14px rgba(139, 92, 246, 0.4);
    }
    .btn-primary:hover {
      background: #7c3aed;
      box-shadow: 0 0 18px var(--accent-cyan);
    }
    .btn-secondary {
      background: transparent;
      border: 1px solid var(--accent-cyan);
      color: var(--accent-cyan);
    }
    .btn-secondary:hover {
      background: rgba(0, 240, 255, 0.12);
      border-color: #fff;
    }

    /* 区块背景图覆盖 */
    .bg-overlay {
      background-size: cover;
      background-position: center;
      position: relative;
    }
    .bg-overlay::before {
      content: '';
      position: absolute;
      inset: 0;
      background: radial-gradient(circle at 30% 30%, rgba(139, 92, 246, 0.18), transparent 70%);
    }

    footer {
      background: #0A0818;
      padding: 32px 0;
      text-align: center;
      border-top: 1px solid rgba(139, 92, 246, 0.3);
      font-size: 0.9rem;
      color: var(--text-secondary);
    }

    /* 对比表等自定义 */
    .comparison-table {
      display: grid;
      grid-template-columns: 1fr auto 1fr;
      gap: 24px;
      align-items: center;
    }
    @media (max-width: 768px) {
      .comparison-table {
        grid-template-columns: 1fr;
      }
      h1 {
        font-size: 2rem;
      }
    }