/* roulang page: index */
/* ===== CSS 变量 & 设计令牌 ===== */
    :root {
      --color-bg-primary: #0A1A2F;
      --color-bg-card: rgba(10, 26, 47, 0.6);
      --color-accent: #00E5FF;
      --color-accent-glow: rgba(0, 229, 255, 0.4);
      --color-text-primary: #FFFFFF;
      --color-text-secondary: #B0C4DE;
      --color-text-highlight: #E8F4FD;
      --color-border: rgba(0, 229, 255, 0.18);
      --color-dark-footer: #060F1A;
      
      --glass-blur: blur(18px);
      --card-radius: 16px;
      --btn-radius: 8px;
      
      --font-sans: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", system-ui, -apple-system, sans-serif;
      --font-mono: "Inter", "SF Mono", "DIN Alternate", "Fira Code", monospace;
      
      --transition-smooth: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
      --container-max: 1200px;
      --section-gap: 5rem;
    }

    /* ===== 全局重置 ===== */
    *, *::before, *::after {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

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

    body {
      font-family: var(--font-sans);
      background-color: var(--color-bg-primary);
      color: var(--color-text-secondary);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
      background-image: 
        linear-gradient(rgba(0, 229, 255, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(0, 229, 255, 0.03) 1px, transparent 1px);
      background-size: 44px 44px;
      background-position: center center;
    }

    /* 容器 */
    .container {
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 24px;
    }
    @media (max-width: 768px) {
      .container {
        padding: 0 18px;
      }
    }

    /* 排版基础 */
    h1, h2, h3, h4 {
      color: var(--color-text-primary);
      font-weight: 600;
      letter-spacing: -0.2px;
    }
    h1 { font-size: clamp(2.4rem, 5vw, 3.25rem); font-weight: 700; }
    h2 { font-size: clamp(2rem, 4vw, 2.5rem); margin-bottom: 1rem; }
    h3 { font-size: 1.4rem; }
    p { margin-bottom: 0.8rem; }

    /* 链接与按钮通用 */
    a {
      color: var(--color-text-secondary);
      text-decoration: none;
      transition: var(--transition-smooth);
    }
    a:hover { color: var(--color-accent); }
    
    /* 按钮组件 */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 0.75rem 2rem;
      font-weight: 600;
      border-radius: var(--btn-radius);
      font-size: 1rem;
      transition: all var(--transition-smooth);
      cursor: pointer;
      border: none;
      background: transparent;
      line-height: 1.4;
    }
    .btn-primary {
      background: var(--color-accent);
      color: #0A1A2F;
      box-shadow: 0 4px 14px rgba(0, 229, 255, 0.3);
    }
    .btn-primary:hover {
      box-shadow: 0 0 24px var(--color-accent-glow), 0 6px 20px rgba(0, 229, 255, 0.5);
      transform: scale(1.03);
      background: #19f0ff;
    }
    .btn-outline {
      border: 2px solid var(--color-text-highlight);
      color: var(--color-text-highlight);
      backdrop-filter: blur(12px);
    }
    .btn-outline:hover {
      background: rgba(232, 244, 253, 0.08);
      border-color: var(--color-accent);
      color: var(--color-accent);
      transform: translateY(-2px);
    }
    .btn:active {
      transform: scale(0.97);
    }

    /* 玻璃卡片基础 */
    .glass-card {
      background: var(--color-bg-card);
      backdrop-filter: var(--glass-blur);
      -webkit-backdrop-filter: var(--glass-blur);
      border: 1px solid var(--color-border);
      border-radius: var(--card-radius);
      box-shadow: 0 12px 32px rgba(0, 0, 0, 0.5);
      transition: var(--transition-smooth);
    }
    .glass-card:hover {
      box-shadow: 0 16px 40px rgba(0, 0, 0, 0.6), 0 0 18px rgba(0, 229, 255, 0.22);
    }

    /* 导航 PDF 规范定制 */
    .navbar {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 100;
      height: 72px;
      background: rgba(10, 26, 47, 0.78);
      backdrop-filter: blur(28px);
      -webkit-backdrop-filter: blur(28px);
      border-bottom: 1px solid rgba(0, 229, 255, 0.18);
    }
    .nav-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 100%;
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 24px;
    }
    .logo {
      display: flex;
      align-items: center;
      gap: 10px;
      font-size: 1.45rem;
      font-weight: 700;
      color: #fff;
    }
    .logo svg { width: 36px; height: 36px; fill: var(--color-accent); }
    .nav-links { display: flex; gap: 2.2rem; align-items: center; font-weight: 500; }
    .nav-links a { padding: 6px 0; position: relative; }
    .nav-links a.active-nav, .nav-links a:hover {
      color: var(--color-accent);
    }
    .hamburger { display: none; background: none; border: none; cursor: pointer; padding: 10px; }
    .hamburger span { display: block; width: 26px; height: 2px; background: var(--color-accent); margin: 6px 0; transition: 0.25s;}
    
    @media (max-width: 768px) {
      .nav-links { display: none; }
      .hamburger { display: block; }
      .mobile-menu {
        position: fixed; top: 72px; left: 0; width: 100%; background: rgba(6, 15, 26, 0.96);
        backdrop-filter: blur(30px); display: flex; flex-direction: column; padding: 2rem;
        gap: 2rem; font-size: 1.3rem; display: none; border-bottom: 1px solid rgba(0,229,255,0.3);
      }
      .mobile-menu.active { display: flex; }
    }

    /* HERO 区域 + 背景图加载 */
    .hero {
      padding: 140px 0 100px;
      color: #fff;
      position: relative;
      background-image: url('/assets/images/backpic/back-1.webp');
      background-size: cover;
      background-position: center;
      background-repeat: no-repeat;
      background-blend-mode: overlay;
      background-color: var(--color-bg-primary);
      overflow: hidden;
    }
    .hero::before {
      content: '';
      position: absolute;
      inset: 0;
      background: radial-gradient(circle at 75% 30%, rgba(0, 229, 255, 0.15) 0%, transparent 60%);
      pointer-events: none;
    }
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 3.5rem;
      align-items: center;
      position: relative;
      z-index: 2;
    }
    .hero-left h1 { font-size: 3.4rem; line-height: 1.2; margin-bottom: 1.2rem; }
    .hero-buttons { display: flex; gap: 1rem; flex-wrap: wrap; margin-top: 2rem; }
    
    .hero-stat-card {
      background: rgba(10, 26, 47, 0.65);
      backdrop-filter: blur(20px);
      border-radius: 24px;
      border: 1px solid rgba(0,229,255,0.3);
      padding: 2rem;
    }
    .stat-row { display: flex; justify-content: space-between; margin: 0.8rem 0; }
    .stat-value { font-family: var(--font-mono); font-size: 2.3rem; font-weight: 700; color: var(--color-accent); }
    
    @media (max-width: 900px) {
      .hero-grid { grid-template-columns: 1fr; }
    }

    /* 通用板块 */
    section { padding: 4.8rem 0; }
    .section-title { text-align: center; margin-bottom: 3rem; }
    .grid-3, .grid-2 { display: grid; gap: 2rem; }
    .grid-3 { grid-template-columns: repeat(3,1fr); }
    .grid-2 { grid-template-columns: repeat(2,1fr); }
    
    /* 服务卡片带图 */
    .service-card { padding: 2rem 1.75rem; text-align: left; }
    .card-icon { font-size: 2.6rem; color: var(--color-accent); margin-bottom: 1.2rem; }
    .tech-tag {
      background: rgba(0,229,255,0.12); color: var(--color-accent); padding: 4px 12px;
      border-radius: 40px; font-size: 0.7rem; letter-spacing: 0.8px; font-weight: 600;
    }
    .cover-img { width: 100%; border-radius: 12px; margin: 1rem 0; border: 1px solid rgba(255,255,255,0.1); }

    @media (max-width: 900px) {
      .grid-3 { grid-template-columns: repeat(2,1fr); }
    }
    @media (max-width: 600px) {
      .grid-3, .grid-2 { grid-template-columns: 1fr; }
    }

    /* Footer */
    .footer-grid { display: grid; grid-template-columns: 1.5fr 1fr 1fr 1fr; gap: 2.5rem; padding: 3rem 0; }
    .footer-bottom { border-top: 1px solid rgba(255,255,255,0.1); padding: 1.5rem 0; text-align: center; color: #7f8ea0; }
    @media (max-width: 768px) {
      .footer-grid { grid-template-columns: 1fr 1fr; }
    }