/* roulang page: index */
:root {
      --primary: #3D5AFE;
      --primary-hover: #2B47D9;
      --accent: #FF6D3F;
      --bg: #F5F6FA;
      --card: #FFFFFF;
      --dark: #1A1F36;
      --text: #1F2329;
      --text-secondary: #6B7280;
      --border-light: #E5E7EB;
      --disabled: #D1D5DB;
      --success: #00B578;
      --warning: #FF9F0A;
      --error: #FA5151;
      --radius: 12px;
      --shadow-card: 0 2px 12px rgba(0,0,0,0.04);
      --shadow-hover: 0 4px 20px rgba(61,90,254,0.12);
      --transition: 250ms cubic-bezier(0.4, 0, 0.2, 1);
      --font-family: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    html {
      scroll-behavior: smooth;
    }
    body {
      font-family: var(--font-family);
      background-color: var(--bg);
      color: var(--text);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
      overflow-x: hidden;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
    }
    ul {
      list-style: none;
    }
    button, .btn {
      cursor: pointer;
      font-family: inherit;
      border: none;
      outline: none;
      transition: var(--transition);
    }
    .container {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 24px;
    }
    @media (max-width: 768px) {
      .container {
        padding: 0 16px;
      }
    }

    /* 导航 */
    .nav {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 64px;
      z-index: 100;
      background: rgba(255,255,255,0.7);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      border-bottom: 1px solid transparent;
      transition: background var(--transition), box-shadow var(--transition), border-color var(--transition);
      display: flex;
      align-items: center;
    }
    .nav.scrolled {
      background: rgba(255,255,255,0.95);
      box-shadow: 0 2px 12px rgba(0,0,0,0.04);
      border-bottom: 1px solid var(--border-light);
    }
    .nav .container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
    }
    .logo {
      display: flex;
      align-items: center;
      gap: 8px;
      font-weight: 700;
      font-size: 22px;
      color: var(--text);
    }
    .logo-icon {
      width: 32px;
      height: 32px;
      background: var(--primary);
      border-radius: 8px;
      display: flex;
      align-items: center;
      justify-content: center;
      color: white;
      font-size: 18px;
      font-weight: 700;
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 32px;
    }
    .nav-links a {
      font-size: 15px;
      font-weight: 500;
      color: var(--text);
      position: relative;
      padding: 8px 0;
      transition: color var(--transition);
    }
    .nav-links a:hover,
    .nav-links a.active {
      color: var(--primary);
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--primary);
      transition: width var(--transition);
    }
    .nav-links a:hover::after,
    .nav-links a.active::after {
      width: 100%;
    }
    .btn-primary {
      background: var(--primary);
      color: white;
      border-radius: 8px;
      padding: 12px 24px;
      font-weight: 500;
      font-size: 15px;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      transition: background var(--transition), box-shadow var(--transition), transform var(--transition);
      white-space: nowrap;
      min-width: 100px;
    }
    .btn-primary:hover {
      background: var(--primary-hover);
      box-shadow: 0 6px 20px rgba(61,90,254,0.3);
      transform: translateY(-1px);
    }
    .btn-primary:active {
      transform: scale(0.97);
    }
    .btn-outline {
      background: transparent;
      border: 1.5px solid var(--primary);
      color: var(--primary);
      border-radius: 8px;
      padding: 12px 24px;
      font-weight: 500;
      font-size: 15px;
      transition: background var(--transition), color var(--transition);
    }
    .btn-outline:hover {
      background: rgba(61,90,254,0.08);
    }
    .btn-ghost {
      background: transparent;
      border: 1.5px solid white;
      color: white;
      border-radius: 8px;
      padding: 12px 24px;
      font-weight: 500;
    }
    .btn-ghost:hover {
      background: rgba(255,255,255,0.15);
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      background: none;
      border: none;
      padding: 4px;
      cursor: pointer;
    }
    .hamburger span {
      width: 24px;
      height: 2px;
      background: var(--text);
      transition: var(--transition);
    }
    @media (max-width: 1024px) {
      .nav-links {
        display: none;
      }
      .hamburger {
        display: flex;
      }
      .nav .btn-primary.desktop-cta {
        display: none;
      }
    }
    .mobile-menu {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100vh;
      background: white;
      z-index: 99;
      display: flex;
      flex-direction: column;
      padding: 24px;
      transform: translateX(100%);
      transition: transform var(--transition);
    }
    .mobile-menu.open {
      transform: translateX(0);
    }
    .mobile-menu a {
      font-size: 20px;
      padding: 16px 0;
      border-bottom: 1px solid var(--border-light);
      color: var(--text);
      font-weight: 500;
    }
    .mobile-menu .btn-primary {
      margin-top: 24px;
      width: 100%;
    }

@media (max-width: 1024px) {
          .features-grid {
            grid-template-columns: repeat(2, 1fr);
          }
        }
        @media (max-width: 640px) {
          .features-grid {
            display: flex;
            overflow-x: auto;
            gap: 16px;
            grid-template-columns: unset;
            scroll-snap-type: x mandatory;
          }
          .features-grid > div {
            scroll-snap-align: start;
            flex: 0 0 260px;
          }
        }