/* roulang page: index */
/* 设计变量与全局重置 */
    :root {
      --primary: #4E6EF2;
      --primary-light: rgba(78, 110, 242, 0.1);
      --primary-glow: rgba(78, 110, 242, 0.2);
      --secondary: #00B578;
      --warning: #FF9F0A;
      --danger: #FA5151;
      --bg: #F5F6FA;
      --card-bg: #FFFFFF;
      --text-primary: #1F2329;
      --text-secondary: #86909C;
      --border-light: #E5E8EF;
      --shadow-sm: 0 2px 8px rgba(0,0,0,0.04);
      --shadow-md: 0 8px 24px rgba(0,0,0,0.08);
      --radius-lg: 12px;
      --radius-btn: 8px;
      --radius-capsule: 50px;
      --transition: 200ms ease-out;
      --font-stack: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
    }
    * {
      box-sizing: border-box;
    }
    body {
      margin: 0;
      font-family: var(--font-stack);
      background-color: var(--bg);
      color: var(--text-primary);
      line-height: 1.5;
      -webkit-font-smoothing: antialiased;
    }
    img {
      max-width: 100%;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: color var(--transition);
    }
    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 24px;
    }
    @media (max-width: 768px) {
      .container {
        padding: 0 16px;
      }
      h1 {
        font-size: 28px !important;
        line-height: 1.3 !important;
      }
      h2 {
        font-size: 24px !important;
      }
      .hero-desc {
        font-size: 15px !important;
      }
    }
    /* 导航系统 */
    .navbar {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 64px;
      background: white;
      z-index: 50;
      transition: box-shadow var(--transition);
      display: flex;
      align-items: center;
    }
    .navbar.scrolled {
      box-shadow: 0 2px 12px rgba(0,0,0,0.04);
    }
    .nav-container {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
    }
    .logo {
      font-weight: 700;
      font-size: 22px;
      letter-spacing: -0.3px;
      color: var(--text-primary);
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .logo i {
      color: var(--primary);
      font-size: 26px;
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 28px;
    }
    .nav-links a {
      font-size: 14px;
      font-weight: 500;
      color: var(--text-primary);
      position: relative;
      padding: 4px 0;
    }
    .nav-links a:hover {
      color: var(--primary);
    }
    .nav-links a.active {
      color: var(--primary);
    }
    .nav-links a.active::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 50%;
      transform: translateX(-50%);
      width: 20px;
      height: 2px;
      background: var(--primary);
      border-radius: 2px;
    }
    .btn-capsule {
      background: var(--primary);
      color: white !important;
      padding: 10px 22px;
      border-radius: var(--radius-capsule);
      font-weight: 500;
      font-size: 14px;
      transition: all var(--transition);
      display: inline-block;
    }
    .btn-capsule:hover {
      background: #3A5CD8;
      box-shadow: 0 0 0 3px var(--primary-glow);
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: transparent;
      border: none;
      padding: 4px;
    }
    .hamburger span {
      display: block;
      width: 24px;
      height: 2px;
      background: var(--text-primary);
      transition: var(--transition);
    }
    .mobile-menu {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100vh;
      background: white;
      z-index: 60;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 32px;
      font-size: 20px;
      transform: translateX(100%);
      transition: transform 250ms ease-out;
    }
    .mobile-menu.open {
      transform: translateX(0);
    }
    @media (max-width: 768px) {
      .nav-links {
        display: none;
      }
      .hamburger {
        display: flex;
      }
    }
    /* 按钮体系 */
    .btn-primary {
      background: var(--primary);
      color: white;
      border-radius: var(--radius-btn);
      padding: 12px 24px;
      font-weight: 500;
      display: inline-block;
      transition: all var(--transition);
      border: none;
      cursor: pointer;
    }
    .btn-primary:hover {
      background: #3A5CD8;
      box-shadow: 0 0 0 3px var(--primary-glow);
    }
    .btn-secondary {
      background: transparent;
      border: 1.5px solid var(--primary);
      color: var(--primary);
      border-radius: var(--radius-btn);
      padding: 12px 24px;
      font-weight: 500;
      display: inline-block;
      transition: all var(--transition);
    }
    .btn-secondary:hover {
      background: rgba(78, 110, 242, 0.05);
    }
    /* 卡片系统 */
    .card {
      background: var(--card-bg);
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-sm);
      transition: all var(--transition);
      padding: 24px;
    }
    .card:hover {
      box-shadow: var(--shadow-md);
      transform: translateY(-4px);
    }
    .section-title {
      font-size: 28px;
      font-weight: 600;
      margin-bottom: 16px;
    }
    .section-desc {
      color: var(--text-secondary);
      max-width: 640px;
      margin: 0 auto 40px;
    }
    /* 几何线条动效 */
    .hero-bg {
      position: relative;
      background: #F5F6FA;
      overflow: hidden;
    }
    .hero-bg::before {
      content: '';
      position: absolute;
      width: 200%;
      height: 200%;
      top: -50%;
      left: -50%;
      background: radial-gradient(circle at 30% 40%, rgba(78,110,242,0.06) 0%, transparent 50%);
      animation: floatLines 18s infinite alternate ease-in-out;
    }
    @keyframes floatLines {
      0% { transform: translate(0,0) rotate(0deg); }
      100% { transform: translate(-2%, -1%) rotate(1deg); }
    }
    .faq-item {
      border-bottom: 1px solid var(--border-light);
    }
    .faq-question {
      cursor: pointer;
      padding: 16px 0;
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-weight: 600;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease-out;
      color: var(--text-secondary);
      padding: 0 0 0 0;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-bottom: 16px;
    }
    footer a:hover {
      color: var(--primary);
    }