/* roulang page: index */
:root {
      --primary: #1A5F7A;
      --primary-hover: #134B62;
      --accent: #F39C12;
      --accent-hover: #E67E22;
      --soft: #E8F4F8;
      --dark: #1E293B;
      --gray-light: #F8FAFC;
      --gray-mid: #475569;
      --gray-border: #E2E8F0;
      --text-main: #1E293B;
      --text-secondary: #475569;
      --white: #FFFFFF;
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-input: 6px;
      --shadow-card: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
      --shadow-card-hover: 0 10px 25px -5px rgba(0,0,0,0.1), 0 4px 10px -6px rgba(0,0,0,0.05);
    }
    html {
      scroll-behavior: smooth;
    }
    body {
      font-family: system-ui, -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Inter", sans-serif;
      color: var(--text-main);
      background-color: var(--white);
      line-height: 1.75;
      margin: 0;
      -webkit-font-smoothing: antialiased;
    }
    .container-custom {
      max-width: 1280px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 20px;
      padding-right: 20px;
    }
    @media (min-width: 1024px) {
      .container-custom {
        padding-left: 32px;
        padding-right: 32px;
      }
    }
    h1, h2, h3, h4 {
      font-weight: 600;
    }
    h1 {
      font-size: 2.8rem;
      letter-spacing: -0.5px;
      line-height: 1.3;
    }
    h2 {
      font-size: 2rem;
      margin-bottom: 1rem;
    }
    h3 {
      font-size: 1.25rem;
      font-weight: 600;
    }
    p {
      max-width: 65ch;
      color: var(--text-secondary);
    }
    .section-padding {
      padding-top: 100px;
      padding-bottom: 100px;
    }
    @media (max-width: 768px) {
      h1 {
        font-size: 2.2rem;
      }
      h2 {
        font-size: 1.8rem;
      }
      .section-padding {
        padding-top: 60px;
        padding-bottom: 60px;
      }
    }
    .card-hover:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-card-hover);
      transition: all 0.25s ease;
    }
    .image-hover:hover img {
      transform: scale(1.02);
      transition: transform 0.3s ease;
    }
    .btn-primary {
      background-color: var(--primary);
      color: white;
      border-radius: var(--radius-btn);
      padding: 12px 28px;
      font-weight: 600;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      transition: background-color 0.2s, transform 0.1s, box-shadow 0.2s;
      box-shadow: 0 4px 6px rgba(0,0,0,0.07);
    }
    .btn-primary:hover {
      background-color: var(--primary-hover);
      transform: translateY(-1px);
      box-shadow: 0 10px 15px -3px rgba(0,0,0,0.1);
    }
    .btn-accent {
      background-color: var(--accent);
      color: white;
      border-radius: 6px;
      padding: 10px 24px;
      font-weight: 600;
      transition: background-color 0.2s, transform 0.1s;
      display: inline-block;
      text-align: center;
    }
    .btn-accent:hover {
      background-color: var(--accent-hover);
      transform: translateY(-1px);
    }
    .btn-outline {
      background: transparent;
      border: 2px solid var(--primary);
      color: var(--primary);
      border-radius: var(--radius-btn);
      padding: 10px 26px;
      font-weight: 600;
      transition: all 0.2s;
    }
    .btn-outline:hover {
      background-color: rgba(26,95,122,0.05);
      border-color: var(--primary-hover);
      color: var(--primary-hover);
    }
    .faq-item {
      border-bottom: 1px solid var(--gray-border);
    }
    .faq-question {
      cursor: pointer;
      padding: 20px 0;
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      align-items: center;
      color: var(--text-main);
      transition: color 0.2s;
    }
    .faq-question:hover {
      color: var(--primary);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease, padding 0.2s;
      color: var(--text-secondary);
    }
    .faq-item.active .faq-answer {
      max-height: 300px;
      padding-bottom: 20px;
    }
    .faq-icon {
      font-size: 1.4rem;
      font-weight: 400;
      transition: transform 0.2s;
    }
    .faq-item.active .faq-icon {
      transform: rotate(45deg);
    }
    .nav-link {
      color: var(--text-secondary);
      font-weight: 500;
      transition: color 0.2s;
      padding: 0.5rem 0;
    }
    .nav-link:hover {
      color: var(--primary);
    }
    #mobile-menu {
      transition: all 0.3s ease;
    }
    .compare-highlight {
      background-color: var(--soft);
      border-top: 3px solid var(--primary);
    }