/* roulang page: index */
/* 基础重置与设计变量 */
    :root {
      --primary: #1A3A5C;
      --secondary: #4A90B8;
      --accent: #D4A843;
      --bg: #F7F9FC;
      --text-main: #1E2A36;
      --text-soft: #5A6978;
      --text-light: #8B9AAB;
      --footer-dark: #1E2A36;
      --card-radius: 12px;
      --btn-radius: 8px;
      --transition: 0.25s ease;
    }
    
    * {
      box-sizing: border-box;
    }
    
    body {
      font-family: 'Inter', 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', 'Segoe UI', sans-serif;
      color: var(--text-main);
      background-color: var(--bg);
      line-height: 1.7;
      margin: 0;
      padding: 0;
      -webkit-font-smoothing: antialiased;
    }
    
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    
    a {
      text-decoration: none;
      color: inherit;
      transition: color var(--transition);
    }
    
    button, input, textarea {
      font-family: inherit;
    }
    
    .container {
      max-width: 1200px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 1.5rem;
      padding-right: 1.5rem;
    }
    
    /* 导航固定与样式 */
    .header-nav {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background: #FFFFFF;
      box-shadow: 0 1px 0 rgba(0,0,0,0.05);
      z-index: 50;
      height: 72px;
      display: flex;
      align-items: center;
    }
    
    .nav-logo {
      font-size: 22px;
      font-weight: 700;
      color: var(--primary);
      letter-spacing: 0.5px;
      display: flex;
      align-items: center;
      gap: 6px;
    }
    
    .nav-logo i {
      color: var(--accent);
      font-size: 20px;
    }
    
    .nav-link {
      font-size: 15px;
      font-weight: 500;
      color: var(--text-main);
      padding: 0.5rem 0.8rem;
      transition: color var(--transition);
      white-space: nowrap;
    }
    
    .nav-link:hover {
      color: var(--secondary);
    }
    
    /* 移动端菜单 */
    .mobile-menu {
      display: none;
      position: fixed;
      top: 72px;
      left: 0;
      width: 100%;
      background: #FFFFFF;
      box-shadow: 0 10px 25px rgba(0,0,0,0.08);
      flex-direction: column;
      padding: 1.5rem;
      z-index: 40;
    }
    
    .mobile-menu.active {
      display: flex;
    }
    
    .mobile-menu a {
      padding: 0.8rem 0;
      font-size: 18px;
      border-bottom: 1px solid #f0f2f5;
      color: var(--text-main);
    }
    
    /* 汉堡按钮 */
    .hamburger {
      display: none;
      font-size: 24px;
      background: none;
      border: none;
      color: var(--primary);
      cursor: pointer;
    }
    
    /* 卡片悬停动效 */
    .card-hover {
      transition: transform var(--transition), box-shadow var(--transition);
    }
    
    .card-hover:hover {
      transform: translateY(-4px);
      box-shadow: 0 8px 30px rgba(26,58,92,0.12);
    }
    
    /* 按钮样式 */
    .btn-primary {
      background: var(--primary);
      color: white;
      font-weight: 600;
      font-size: 16px;
      padding: 12px 28px;
      border-radius: var(--btn-radius);
      display: inline-block;
      transition: background var(--transition);
      border: none;
      cursor: pointer;
    }
    
    .btn-primary:hover {
      background: #152E4A;
    }
    
    .btn-outline {
      background: transparent;
      color: var(--primary);
      font-weight: 600;
      font-size: 16px;
      padding: 12px 28px;
      border-radius: var(--btn-radius);
      border: 2px solid var(--primary);
      display: inline-block;
      transition: all var(--transition);
    }
    
    .btn-outline:hover {
      background: rgba(26,58,92,0.05);
    }
    
    .btn-accent {
      background: var(--accent);
      color: white;
      font-weight: 600;
      font-size: 16px;
      padding: 12px 28px;
      border-radius: var(--btn-radius);
      display: inline-block;
      transition: filter var(--transition);
      border: none;
      cursor: pointer;
    }
    
    .btn-accent:hover {
      filter: brightness(1.1);
    }
    
    /* FAQ 手风琴 */
    .faq-item {
      border-bottom: 1px solid #E2E8F0;
    }
    
    .faq-question {
      padding: 16px 0;
      font-weight: 600;
      font-size: 18px;
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
      color: var(--text-main);
    }
    
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease, padding 0.3s ease;
      color: var(--text-soft);
    }
    
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-bottom: 16px;
    }
    
    .faq-item.active .faq-icon {
      transform: rotate(45deg);
    }
    
    .faq-icon {
      transition: transform 0.3s;
      font-size: 20px;
      color: var(--secondary);
    }
    
    /* 输入框 */
    .form-input {
      width: 100%;
      padding: 12px 16px;
      border: 1px solid #D0D7DE;
      border-radius: 8px;
      background: white;
      transition: border var(--transition);
      outline: none;
    }
    
    .form-input:focus {
      border-color: var(--secondary);
      box-shadow: 0 0 0 3px rgba(74,144,184,0.1);
    }
    
    @media (max-width: 768px) {
      .hamburger {
        display: block;
      }
      .desktop-menu {
        display: none;
      }
      .section-padding {
        padding-top: 60px;
        padding-bottom: 60px;
      }
      h1 {
        font-size: 32px !important;
      }
      h2 {
        font-size: 24px !important;
      }
      h3 {
        font-size: 18px !important;
      }
    }
    
    @media (min-width: 769px) {
      .mobile-menu {
        display: none !important;
      }
    }