/* roulang page: index */
/* 设计变量 */
    :root {
      --primary: #0A7EA4;
      --primary-deep: #086A8C;
      --accent: #F85C3C;
      --accent-deep: #D93E26;
      --bg-light: #F7F8FA;
      --card-bg: #FFFFFF;
      --text-primary: #222;
      --text-body: #444444;
      --text-muted: #777777;
      --border-light: #E0E4E8;
      --border-focus: #0A7EA4;
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-input: 8px;
      --shadow-sm: 0 2px 12px rgba(0, 0, 0, 0.06);
      --shadow-hover: 0 8px 24px rgba(10, 126, 164, 0.12);
      --font-title: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --transition: 0.25s ease-out;
      --container-max: 1200px;
    }

    /* Reset & Base */
    *, *::before, *::after {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    html {
      scroll-behavior: smooth;
    }

    body {
      font-family: var(--font-title);
      background-color: #FFFFFF;
      color: var(--text-body);
      line-height: 1.8;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }

    a {
      text-decoration: none;
      color: inherit;
    }

    img {
      max-width: 100%;
      height: auto;
      display: block;
    }

    button, input, textarea {
      font-family: inherit;
      font-size: inherit;
    }

    .container {
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 24px;
    }

    /* 标题层级 */
    h1, h2, h3, h4 {
      font-family: var(--font-title);
      font-weight: 600;
      color: var(--text-primary);
    }

    h1 {
      font-size: 40px;
      font-weight: 700;
      line-height: 1.3;
    }

    h2 {
      font-size: 32px;
      font-weight: 600;
      margin-bottom: 16px;
    }

    h3 {
      font-size: 20px;
      font-weight: 600;
    }

    /* 按钮系统 */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 12px 28px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      transition: background-color 0.2s, color 0.2s, border-color 0.2s, box-shadow 0.2s;
      cursor: pointer;
      font-size: 16px;
      border: 1.5px solid transparent;
      background: transparent;
      text-align: center;
    }

    .btn-primary {
      background-color: var(--accent);
      color: white;
      border-color: var(--accent);
    }
    .btn-primary:hover {
      background-color: var(--accent-deep);
      border-color: var(--accent-deep);
      box-shadow: 0 4px 14px rgba(248, 92, 60, 0.3);
    }

    .btn-outline {
      border-color: var(--primary);
      color: var(--primary);
      background: transparent;
    }
    .btn-outline:hover {
      background-color: rgba(10, 126, 164, 0.06);
      border-color: var(--primary-deep);
      color: var(--primary-deep);
    }

    .btn-large {
      padding: 14px 36px;
      font-size: 17px;
    }

    /* 导航 */
    .header {
      position: sticky;
      top: 0;
      z-index: 100;
      background-color: white;
      box-shadow: 0 1px 0 rgba(0,0,0,0.05);
      height: 64px;
      display: flex;
      align-items: center;
      transition: box-shadow 0.2s;
    }
    .header.scrolled {
      box-shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
    }
    .nav-container {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
    }
    .logo {
      font-size: 24px;
      font-weight: 700;
      color: var(--text-primary);
      letter-spacing: 1px;
      display: flex;
      align-items: center;
    }
    .logo span {
      color: var(--primary);
      font-weight: 700;
    }
    .nav-links {
      display: flex;
      gap: 32px;
      align-items: center;
    }
    .nav-links a {
      font-weight: 500;
      color: var(--text-body);
      position: relative;
      padding: 4px 0;
      transition: color 0.2s;
      font-size: 16px;
    }
    .nav-links a:hover,
    .nav-links a.active {
      color: var(--primary);
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 0%;
      height: 2px;
      background-color: var(--primary);
      transition: width 0.25s ease;
    }
    .nav-links a:hover::after {
      width: 100%;
    }

    .mobile-toggle {
      display: none;
      background: none;
      border: none;
      font-size: 28px;
      color: var(--text-primary);
      cursor: pointer;
    }

    @media (max-width: 768px) {
      .mobile-toggle {
        display: block;
      }
      .nav-links {
        display: none;
        position: fixed;
        top: 64px;
        left: 0;
        width: 100%;
        height: calc(100vh - 64px);
        background: rgba(255,255,255,0.97);
        backdrop-filter: blur(10px);
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: 32px;
        z-index: 99;
      }
      .nav-links.active {
        display: flex;
      }
    }

    /* 板块间距 */
    .section {
      padding: 80px 0;
    }
    @media (max-width: 768px) {
      .section {
        padding: 60px 0;
      }
      h1 {
        font-size: 32px;
      }
      h2 {
        font-size: 28px;
      }
    }

    /* Hero 双栏 */
    .hero-grid {
      display: flex;
      align-items: center;
      gap: 48px;
    }
    .hero-left {
      flex: 1 1 45%;
    }
    .hero-right {
      flex: 1 1 50%;
      position: relative;
    }
    .hero-image {
      width: 100%;
      aspect-ratio: 4 / 3;
      object-fit: cover;
      border-radius: 18px;
      box-shadow: 0 20px 30px rgba(0,0,0,0.12);
      background: #e0e9f0; /* 图片占位底色 */
      display: block;
    }
    .hero-title {
      margin-bottom: 20px;
      color: #0A1E2F; /* 深色加强对比 */
    }
    .hero-desc {
      font-size: 18px;
      color: var(--text-muted);
      margin-bottom: 32px;
      max-width: 90%;
    }
    .hero-cta {
      display: flex;
      gap: 20px;
      flex-wrap: wrap;
      margin-bottom: 36px;
    }
    .trust-badge {
      display: flex;
      align-items: center;
      gap: 18px;
      color: var(--text-muted);
      font-size: 14px;
      flex-wrap: wrap;
    }
    .trust-badge i {
      font-size: 24px;
      color: var(--primary);
      opacity: 0.7;
    }

    @media (max-width: 768px) {
      .hero-grid {
        flex-direction: column;
        gap: 32px;
      }
      .hero-image {
        aspect-ratio: 16/9;
      }
      .hero-desc {
        max-width: 100%;
      }
    }

    /* 优势网格 3x2 */
    .advantages-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
      margin-top: 40px;
    }
    .adv-card {
      background: var(--card-bg);
      border-radius: var(--radius-card);
      padding: 32px;
      box-shadow: var(--shadow-sm);
      transition: all 0.3s ease;
      text-align: left;
    }
    .adv-card:hover {
      box-shadow: var(--shadow-hover);
      transform: translateY(-4px);
    }
    .adv-icon {
      font-size: 46px;
      color: var(--primary);
      margin-bottom: 20px;
      opacity: 0.9;
    }
    .adv-title {
      margin-bottom: 10px;
    }

    @media (max-width: 768px) {
      .advantages-grid {
        grid-template-columns: 1fr;
      }
    }

    /* 案例瀑布流三列 */
    .cases-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .case-card {
      background: white;
      border-radius: var(--radius-card);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
      transition: 0.3s ease;
    }
    .case-card:hover {
      box-shadow: var(--shadow-hover);
    }
    .case-img-wrapper {
      position: relative;
      overflow: hidden;
      aspect-ratio: 16 / 9;
      background: #d9e1e8;
    }
    .case-img {
      width: 100%;
      height: 100%;
      object-fit: cover;
      transition: transform 0.35s ease;
    }
    .case-card:hover .case-img {
      transform: scale(1.03);
    }
    .case-info {
      padding: 20px;
    }
    .case-tag {
      display: inline-block;
      background: rgba(248, 92, 60, 0.1);
      color: var(--accent);
      font-size: 13px;
      font-weight: 600;
      padding: 4px 12px;
      border-radius: 20px;
      margin-bottom: 8px;
    }
    .case-name {
      font-weight: 650;
      margin: 8px 0 4px;
    }
    .case-desc {
      font-size: 15px;
      color: var(--text-muted);
    }
    @media (max-width: 768px) {
      .cases-grid {
        grid-template-columns: 1fr;
      }
    }

    /* 对比表 */
    .compare-wrapper {
      display: flex;
      gap: 32px;
      margin-top: 32px;
    }
    .compare-col {
      flex: 1;
      border-radius: var(--radius-card);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
      background: white;
    }
    .compare-header {
      padding: 20px;
      font-weight: 700;
      font-size: 18px;
      background: #F0F2F5;
      text-align: center;
      color: var(--text-body);
    }
    .compare-col.right .compare-header {
      background: #E8F4F8;
      color: #0A5E7A;
    }
    .compare-row {
      display: flex;
      justify-content: space-between;
      padding: 16px 24px;
      border-bottom: 1px solid #eee;
      font-size: 15px;
    }
    .check {
      color: var(--primary);
      font-weight: bold;
    }
    .cross {
      color: #aaa;
    }
    @media (max-width: 768px) {
      .compare-wrapper {
        flex-direction: column;
      }
    }

    /* FAQ */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
    }
    .faq-question {
      background: none;
      border: none;
      width: 100%;
      text-align: left;
      padding: 20px 0;
      font-size: 18px;
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
      color: var(--text-primary);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease;
      color: var(--text-body);
      padding-bottom: 0;
    }
    .faq-answer.open {
      max-height: 200px;
      padding-bottom: 20px;
    }

    /* 联系区块 */
    .contact-row {
      display: flex;
      gap: 48px;
      align-items: flex-start;
      margin-top: 32px;
    }
    .contact-form {
      flex: 1;
      display: flex;
      flex-direction: column;
      gap: 18px;
    }
    .form-input {
      height: 48px;
      border: 1px solid #DDD;
      border-radius: var(--radius-input);
      padding: 0 16px;
      width: 100%;
      transition: 0.2s;
      background: white;
    }
    .form-input:focus {
      border-color: var(--border-focus);
      box-shadow: 0 0 0 3px rgba(10,126,164,0.15);
      outline: none;
    }
    .contact-info {
      flex: 0.9;
      background: #F7F8FA;
      padding: 28px;
      border-radius: var(--radius-card);
    }
    @media (max-width: 768px) {
      .contact-row {
        flex-direction: column;
      }
    }

    /* 页脚 */
    .footer {
      background: #EAECF0;
      color: #555;
      padding: 48px 0 24px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 32px;
      margin-bottom: 32px;
    }
    .footer-logo {
      font-size: 22px;
      font-weight: 700;
      color: #222;
    }
    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr;
      }
    }

    textarea.form-input {
      height: 100px;
      padding-top: 12px;
    }

    .badge-light {
      background: rgba(10,126,164,0.08);
      color: #0A5E7A;
      padding: 2px 12px;
      border-radius: 20px;
      font-size: 13px;
    }

    button:focus-visible, a:focus-visible {
      outline: 2px solid var(--primary);
      outline-offset: 2px;
    }