/* roulang page: index */
:root {
      --primary: #D42027;
      --primary-hover: #B01A20;
      --secondary: #1E1E24;
      --accent: #F5A623;
      --bg-warm: #F5F3EF;
      --bg-white: #FFFFFF;
      --text-main: #1E1E24;
      --text-muted: #5A5A66;
      --border-light: #E5E3DF;
      --border-input: #D1CFCB;
      --shadow-sm: 0 2px 12px rgba(0,0,0,0.06);
      --shadow-hover: 0 6px 20px rgba(0,0,0,0.10);
      --radius-card: 12px;
      --radius-btn: 8px;
      --font-sans: 'Inter', 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
      --max-width: 1200px;
      --nav-height: 64px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    body {
      font-family: var(--font-sans);
      font-size: 16px;
      line-height: 1.8;
      color: var(--text-main);
      background-color: var(--bg-white);
      -webkit-font-smoothing: antialiased;
    }
    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }
    a {
      text-decoration: none;
      color: inherit;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    button, .btn {
      cursor: pointer;
      font-family: inherit;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      border: none;
      font-weight: 600;
      transition: all 0.2s ease;
    }
    .btn-primary {
      background-color: var(--primary);
      color: white;
      padding: 12px 28px;
      border-radius: var(--radius-btn);
      font-size: 16px;
      border: 2px solid var(--primary);
    }
    .btn-primary:hover {
      background-color: var(--primary-hover);
      border-color: var(--primary-hover);
      transform: translateY(-1px);
      box-shadow: 0 4px 12px rgba(212,32,39,0.3);
    }
    .btn-outline {
      background: transparent;
      color: var(--secondary);
      padding: 12px 28px;
      border-radius: var(--radius-btn);
      font-size: 16px;
      border: 2px solid var(--secondary);
    }
    .btn-outline:hover {
      background: var(--secondary);
      color: white;
      transform: translateY(-1px);
    }
    .btn-light {
      background: white;
      color: var(--secondary);
      padding: 12px 28px;
      border-radius: var(--radius-btn);
      font-weight: 700;
      border: 2px solid white;
    }
    .btn-light:hover {
      background: #f0f0f0;
      border-color: #f0f0f0;
    }
    h1, h2, h3, h4 {
      font-weight: 600;
      line-height: 1.3;
    }
    .section {
      padding: 100px 0;
    }
    .bg-warm {
      background-color: var(--bg-warm);
    }
    .bg-white {
      background-color: var(--bg-white);
    }
    .bg-dark {
      background-color: var(--secondary);
      color: white;
    }
    /* 导航 */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--nav-height);
      background: white;
      border-bottom: 1px solid var(--border-light);
      z-index: 1000;
      display: flex;
      align-items: center;
    }
    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }
    .logo {
      font-size: 1.5rem;
      font-weight: 700;
      color: var(--primary);
      letter-spacing: 0.5px;
    }
    .logo span {
      color: var(--secondary);
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 32px;
      list-style: none;
    }
    .nav-links a {
      font-weight: 500;
      color: var(--text-main);
      transition: color 0.2s;
      font-size: 16px;
    }
    .nav-links a:hover {
      color: var(--primary);
    }
    .nav-cta {
      margin-left: 16px;
    }
    .hamburger {
      display: none;
      background: none;
      border: none;
      font-size: 24px;
      color: var(--secondary);
      cursor: pointer;
    }
    @media (max-width: 768px) {
      .nav-links {
        display: none;
        position: fixed;
        top: var(--nav-height);
        left: 0;
        width: 100%;
        background: white;
        flex-direction: column;
        padding: 32px 24px;
        gap: 24px;
        border-bottom: 1px solid var(--border-light);
        box-shadow: var(--shadow-sm);
      }
      .nav-links.active {
        display: flex;
      }
      .hamburger {
        display: block;
      }
      .nav-cta.desktop {
        display: none;
      }
    }
    /* Hero */
    .hero-grid {
      display: grid;
      grid-template-columns: 6fr 4fr;
      gap: 60px;
      align-items: center;
    }
    .hero-title {
      font-size: 48px;
      font-weight: 700;
      line-height: 1.2;
      margin-bottom: 24px;
      color: var(--secondary);
    }
    .hero-title .highlight {
      color: var(--primary);
    }
    .hero-sub {
      font-size: 20px;
      color: var(--text-muted);
      margin-bottom: 40px;
    }
    .hero-buttons {
      display: flex;
      gap: 20px;
      flex-wrap: wrap;
    }
    .hero-image {
      width: 100%;
      border-radius: 24px;
      overflow: hidden;
      box-shadow: 0 20px 35px rgba(0,0,0,0.1);
    }
    @media (max-width: 768px) {
      .hero-grid {
        grid-template-columns: 1fr;
        gap: 40px;
      }
      .hero-title {
        font-size: 36px;
      }
    }
    /* 卡片系统 */
    .card {
      background: white;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-sm);
      padding: 32px;
      transition: all 0.25s ease;
      border: 1px solid transparent;
    }
    .card:hover {
      box-shadow: var(--shadow-hover);
      transform: translateY(-4px);
      border-color: var(--border-light);
    }
    .grid-4, .grid-3, .grid-2 {
      display: grid;
      gap: 32px;
    }
    .grid-4 { grid-template-columns: repeat(4, 1fr); }
    .grid-3 { grid-template-columns: repeat(3, 1fr); }
    .grid-2 { grid-template-columns: repeat(2, 1fr); }
    @media (max-width: 1024px) {
      .grid-4 { grid-template-columns: repeat(2, 1fr); }
    }
    @media (max-width: 768px) {
      .grid-4, .grid-3, .grid-2 { grid-template-columns: 1fr; }
    }
    .feature-icon {
      font-size: 40px;
      color: var(--primary);
      margin-bottom: 20px;
    }
    .scenario-img {
      height: 200px;
      background-size: cover;
      background-position: center;
      border-radius: 12px 12px 0 0;
    }
    .case-stat {
      font-size: 42px;
      font-weight: 700;
      color: var(--primary);
      line-height: 1.1;
    }
    .pricing-highlight {
      border: 2px solid var(--primary);
      background: #FFF9F9;
    }
    /* FAQ */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 20px 0;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-weight: 600;
      font-size: 18px;
      cursor: pointer;
      background: none;
      border: none;
      width: 100%;
      text-align: left;
      color: var(--secondary);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease, padding 0.3s ease;
      color: var(--text-muted);
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-top: 16px;
    }
    .footer-cta {
      background: var(--secondary);
      padding: 70px 0;
      text-align: center;
    }
    .input-group {
      display: flex;
      max-width: 400px;
      margin: 20px auto 0;
    }
    .input-group input {
      flex:1;
      height: 48px;
      border: 1px solid var(--border-input);
      border-radius: 8px 0 0 8px;
      padding: 0 16px;
      font-size: 16px;
    }
    .input-group button {
      border-radius: 0 8px 8px 0;
      background: var(--primary);
      color: white;
      border: none;
      padding: 0 24px;
      font-weight: 600;
    }
    footer {
      background: #141418;
      color: #ccc;
      padding: 50px 0 30px;
    }
    @media (max-width: 520px) {
      .hero-title { font-size: 28px; }
    }