/* roulang page: index */
:root {
      --primary-charcoal: #1E1E1E;
      --accent-red: #E63946;
      --accent-red-hover: #c53030;
      --accent-red-light: #FFE5E5;
      --cool-gray: #F5F5F5;
      --light-blue-gray: #A8DADC;
      --pure-white: #FFFFFF;
      --soft-border: #EEEEEE;
      --muted-text: #6B6B6B;
      --footer-bg: #1E1E1E;
      --footer-text: #CCCCCC;
      --shadow-sm: 0 2px 12px rgba(0,0,0,0.04);
      --shadow-md: 0 8px 24px rgba(0,0,0,0.08);
      --shadow-lg: 0 12px 32px rgba(0,0,0,0.12);
      --radius-sm: 6px;
      --radius-md: 8px;
      --radius-lg: 12px;
      --transition-normal: 0.25s ease;
      --transition-fast: 0.2s ease;
      --max-width: 1280px;
    }

    * {
      box-sizing: border-box;
    }

    body {
      margin: 0;
      padding: 0;
      font-family: 'PingFang SC', 'Microsoft YaHei', 'Inter', system-ui, -apple-system, sans-serif;
      background-color: var(--pure-white);
      color: var(--primary-charcoal);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }

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

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

    button, input {
      font-family: inherit;
      outline: none;
    }

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

    /* 导航 */
    .main-header {
      position: sticky;
      top: 0;
      background: var(--pure-white);
      height: 72px;
      border-bottom: 1px solid var(--soft-border);
      z-index: 50;
      transition: box-shadow var(--transition-normal);
      display: flex;
      align-items: center;
    }

    .main-header.scrolled {
      box-shadow: var(--shadow-sm);
    }

    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }

    .nav-logo {
      font-size: 24px;
      font-weight: 700;
      letter-spacing: 0.5px;
      color: var(--primary-charcoal);
      white-space: nowrap;
      order: 2;
      text-align: center;
      flex: 1;
    }

    .nav-logo span {
      color: var(--accent-red);
    }

    .nav-left, .nav-right {
      display: flex;
      align-items: center;
      gap: 32px;
      order: 1;
    }

    .nav-right {
      order: 3;
      justify-content: flex-end;
    }

    .nav-link {
      font-size: 14px;
      font-weight: 500;
      color: var(--primary-charcoal);
      transition: color var(--transition-fast);
      cursor: pointer;
      white-space: nowrap;
    }

    .nav-link:hover {
      color: var(--accent-red);
    }

    .nav-cta-btn {
      background: var(--accent-red);
      color: white;
      padding: 10px 20px;
      border-radius: var(--radius-sm);
      font-size: 14px;
      font-weight: 600;
      transition: background var(--transition-fast), transform var(--transition-fast);
      white-space: nowrap;
      display: inline-block;
    }

    .nav-cta-btn:hover {
      background: var(--accent-red-hover);
      transform: scale(1.02);
    }

    .hamburger {
      display: none;
      background: none;
      border: none;
      font-size: 24px;
      color: var(--primary-charcoal);
      cursor: pointer;
      order: 3;
    }

    /* 移动端菜单 */
    .mobile-menu {
      display: none;
      position: fixed;
      top: 72px;
      left: 0;
      width: 100%;
      background: var(--pure-white);
      box-shadow: var(--shadow-md);
      flex-direction: column;
      align-items: center;
      padding: 24px 0;
      gap: 24px;
      z-index: 49;
    }

    .mobile-menu.open {
      display: flex;
    }

    .mobile-menu .nav-link {
      font-size: 18px;
    }

    .section-spacing {
      padding: 100px 0;
    }

    @media (max-width: 1024px) {
      .nav-left, .nav-right {
        gap: 20px;
      }
      .nav-cta-btn {
        padding: 8px 16px;
        font-size: 13px;
      }
    }

    @media (max-width: 768px) {
      .nav-left, .nav-right {
        display: none;
      }
      .hamburger {
        display: block;
      }
      .nav-container {
        justify-content: space-between;
      }
      .nav-logo {
        order: 2;
        flex: 0 1 auto;
        text-align: center;
      }
      .section-spacing {
        padding: 60px 0;
      }
    }

    /* Hero */
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 48px;
      align-items: center;
    }

    .hero-title {
      font-size: 48px;
      font-weight: 700;
      line-height: 1.2;
      color: var(--primary-charcoal);
      margin-bottom: 20px;
    }

    .hero-title .highlight {
      color: var(--accent-red);
    }

    .hero-sub {
      font-size: 18px;
      color: var(--muted-text);
      margin-bottom: 32px;
      line-height: 1.6;
    }

    .hero-cta-group {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }

    .btn-primary {
      background: var(--accent-red);
      color: white;
      padding: 14px 32px;
      border-radius: var(--radius-sm);
      font-weight: 600;
      font-size: 16px;
      transition: background var(--transition-fast), transform var(--transition-fast), box-shadow var(--transition-fast);
      display: inline-block;
      border: none;
      cursor: pointer;
    }

    .btn-primary:hover {
      background: var(--accent-red-hover);
      transform: scale(1.02);
      box-shadow: 0 0 0 4px rgba(230, 57, 70, 0.2);
    }

    .btn-outline {
      background: transparent;
      color: var(--accent-red);
      border: 1.5px solid var(--accent-red);
      padding: 14px 32px;
      border-radius: var(--radius-sm);
      font-weight: 600;
      font-size: 16px;
      transition: background var(--transition-fast), transform var(--transition-fast);
      display: inline-block;
      cursor: pointer;
    }

    .btn-outline:hover {
      background: var(--accent-red-light);
      transform: scale(1.02);
    }

    .hero-image {
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-md);
      overflow: hidden;
      animation: fadeInUp 0.8s ease;
      background: var(--cool-gray);
    }

    @keyframes fadeInUp {
      0% { opacity: 0; transform: translateY(20px); }
      100% { opacity: 1; transform: translateY(0); }
    }

    .hero-image img {
      width: 100%;
      height: auto;
      object-fit: cover;
      display: block;
    }

    /* 亮点网格 */
    .features-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 0;
      border-top: 1px solid var(--soft-border);
    }

    .feature-item {
      padding: 32px 24px;
      border-bottom: 1px solid var(--soft-border);
      border-right: 1px solid var(--soft-border);
      transition: background var(--transition-normal), transform var(--transition-normal);
    }

    .feature-item:nth-child(4n) {
      border-right: none;
    }

    .feature-item:hover {
      background: #fafafa;
      transform: translateY(-4px);
    }

    .feature-icon {
      font-size: 32px;
      color: var(--accent-red);
      margin-bottom: 16px;
      transition: transform var(--transition-fast);
    }

    .feature-item:hover .feature-icon {
      transform: scale(1.15);
      color: var(--accent-red-hover);
    }

    .feature-title {
      font-size: 18px;
      font-weight: 600;
      color: var(--primary-charcoal);
      margin-bottom: 8px;
      position: relative;
      display: inline-block;
    }

    .feature-item:hover .feature-title::after {
      content: '';
      position: absolute;
      left: 0;
      bottom: -4px;
      width: 24px;
      height: 2px;
      background: var(--accent-red);
      transition: width var(--transition-fast);
    }

    .feature-desc {
      font-size: 14px;
      color: var(--muted-text);
      line-height: 1.5;
    }

    /* 案例瀑布流 */
    .cases-container {
      display: flex;
      flex-direction: column;
      gap: 48px;
    }

    .case-card {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 32px;
      background: var(--pure-white);
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-sm);
      overflow: hidden;
      transition: transform var(--transition-normal), box-shadow var(--transition-normal);
      align-items: center;
    }

    .case-card:nth-child(even) {
      direction: rtl;
    }

    .case-card:nth-child(even) .case-content {
      direction: ltr;
    }

    .case-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-md);
    }

    .case-img {
      height: 280px;
      overflow: hidden;
      background: var(--cool-gray);
    }

    .case-card:hover .case-img img {
      transform: scale(1.03);
    }

    .case-img img {
      width: 100%;
      height: 100%;
      object-fit: cover;
      transition: transform var(--transition-normal);
    }

    .case-content {
      padding: 32px;
      display: flex;
      flex-direction: column;
      justify-content: center;
    }

    .case-tag {
      display: inline-flex;
      gap: 8px;
      margin-bottom: 12px;
    }

    .case-tag span {
      background: #f0f0f0;
      color: var(--muted-text);
      padding: 4px 12px;
      border-radius: 20px;
      font-size: 13px;
      font-weight: 500;
    }

    .case-title {
      font-size: 24px;
      font-weight: 700;
      margin-bottom: 8px;
    }

    .case-year {
      font-size: 14px;
      color: var(--accent-red);
      font-weight: 600;
      margin-bottom: 16px;
    }

    .case-link {
      font-size: 14px;
      font-weight: 600;
      color: var(--accent-red);
      cursor: pointer;
      transition: color var(--transition-fast);
      align-self: flex-start;
    }

    .case-link:hover {
      color: var(--accent-red-hover);
    }

    /* 方案对比 */
    .compare-bg {
      background: var(--cool-gray);
    }

    .compare-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }

    .compare-card {
      background: var(--pure-white);
      border-radius: var(--radius-lg);
      padding: 32px;
      box-shadow: var(--shadow-sm);
      transition: transform var(--transition-normal), box-shadow var(--transition-normal);
      position: relative;
      display: flex;
      flex-direction: column;
    }

    .compare-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-lg);
    }

    .compare-badge {
      background: var(--accent-red);
      color: white;
      font-size: 13px;
      font-weight: 700;
      padding: 4px 16px;
      border-radius: 20px;
      position: absolute;
      top: -12px;
      right: 20px;
    }

    .compare-title {
      font-size: 22px;
      font-weight: 700;
      margin-bottom: 16px;
    }

    .compare-list {
      list-style: none;
      padding: 0;
      margin: 0 0 24px;
      flex: 1;
    }

    .compare-list li {
      padding: 10px 0;
      border-bottom: 1px solid var(--soft-border);
      font-size: 15px;
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .compare-list i.fa-check {
      color: var(--accent-red);
      font-weight: bold;
    }

    .compare-list i.fa-times {
      color: #ccc;
    }

    .compare-cta {
      margin-top: auto;
      text-align: center;
    }

    /* FAQ */
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
      display: flex;
      flex-direction: column;
      gap: 16px;
    }

    .faq-item {
      border-left: 4px solid transparent;
      padding-left: 20px;
      transition: border-color var(--transition-normal);
      cursor: pointer;
    }

    .faq-item.active {
      border-left-color: var(--accent-red);
    }

    .faq-question {
      font-size: 18px;
      font-weight: 600;
      color: var(--primary-charcoal);
      display: flex;
      justify-content: space-between;
      align-items: center;
      padding: 12px 0;
    }

    .faq-arrow {
      transition: transform var(--transition-normal);
    }

    .faq-item.active .faq-arrow {
      transform: rotate(180deg);
    }

    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      color: var(--muted-text);
      line-height: 1.6;
    }

    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-bottom: 12px;
    }

    /* 联系 */
    .contact-form {
      max-width: 500px;
      margin: 0 auto;
      display: flex;
      gap: 12px;
    }

    .input-underline {
      flex: 1;
      border: none;
      border-bottom: 2px solid #ddd;
      padding: 12px 8px;
      font-size: 16px;
      transition: border-color var(--transition-fast);
      background: transparent;
    }

    .input-underline:focus {
      border-bottom-color: var(--accent-red);
      outline: none;
    }

    .contact-info {
      display: flex;
      justify-content: center;
      gap: 40px;
      margin-top: 32px;
      flex-wrap: wrap;
      color: var(--muted-text);
    }

    .social-icons {
      display: flex;
      gap: 16px;
      justify-content: center;
      margin-top: 20px;
    }

    .social-icon {
      width: 40px;
      height: 40px;
      border-radius: 50%;
      border: 1px solid #ddd;
      display: flex;
      align-items: center;
      justify-content: center;
      color: #aaa;
      transition: all var(--transition-fast);
    }

    .social-icon:hover {
      background: var(--accent-red);
      border-color: var(--accent-red);
      color: white;
    }

    /* 页脚 */
    .footer {
      background: var(--footer-bg);
      color: var(--footer-text);
      padding: 60px 0 30px;
    }

    .footer-grid {
      display: grid;
      grid-template-columns: 1.5fr 1fr 1fr 1fr;
      gap: 32px;
    }

    .footer-logo {
      font-size: 22px;
      font-weight: 700;
      color: white;
      margin-bottom: 12px;
    }

    .footer-desc {
      font-size: 14px;
      line-height: 1.5;
    }

    .footer-title {
      font-weight: 600;
      color: white;
      margin-bottom: 16px;
      font-size: 16px;
    }

    .footer-links {
      list-style: none;
      padding: 0;
    }

    .footer-links li {
      margin-bottom: 10px;
    }

    .footer-links a {
      color: var(--footer-text);
      font-size: 14px;
      transition: color var(--transition-fast);
    }

    .footer-links a:hover {
      color: var(--accent-red);
    }

    .copyright {
      border-top: 1px solid #333;
      margin-top: 40px;
      padding-top: 20px;
      text-align: center;
      font-size: 12px;
    }

    @media (max-width: 768px) {
      .hero-grid {
        grid-template-columns: 1fr;
      }
      .features-grid {
        grid-template-columns: 1fr 1fr;
      }
      .feature-item:nth-child(2n) {
        border-right: none;
      }
      .case-card {
        grid-template-columns: 1fr;
        direction: ltr;
      }
      .case-card:nth-child(even) {
        direction: ltr;
      }
      .compare-grid {
        grid-template-columns: 1fr;
      }
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
      .contact-form {
        flex-direction: column;
        padding: 0 20px;
      }
    }

    @media (max-width: 520px) {
      .features-grid {
        grid-template-columns: 1fr;
      }
      .feature-item {
        border-right: none;
      }
      .footer-grid {
        grid-template-columns: 1fr;
      }
    }