/* roulang page: index */
/* ----- 设计变量 ----- */
    :root {
      --primary-red: #E53935;
      --primary-red-hover: #C62828;
      --primary-red-light: #FFEBEE;
      --dark-indigo: #1B1B2F;
      --accent-amber: #FFB300;
      --white: #FFFFFF;
      --bg-light: #FAFAFA;
      --bg-expand: #F5F5F5;
      --text-dark: #1B1B2F;
      --text-mid: #4A4A5A;
      --text-gray: #8E8E9A;
      --text-footer: #B0B0B0;
      --border-light: #E8E8EF;
      --shadow-card: 0 4px 20px rgba(0,0,0,0.06);
      --shadow-hover: 0 8px 30px rgba(0,0,0,0.12);
      --radius-card: 12px;
      --radius-btn: 8px;
      --transition: 0.3s ease;
      --container-max: 1200px;
      --nav-height: 72px;
    }

    /* ----- 基础重置与排版 ----- */
    *, *::before, *::after {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    html {
      scroll-behavior: smooth;
    }

    body {
      font-family: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      background-color: var(--white);
      color: var(--text-mid);
      font-size: 16px;
      line-height: 1.8;
      font-weight: 400;
      -webkit-font-smoothing: antialiased;
    }

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

    a {
      text-decoration: none;
      color: inherit;
      transition: color var(--transition);
    }

    button, .btn {
      cursor: pointer;
      font-family: inherit;
      border: none;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      font-weight: 500;
      border-radius: var(--radius-btn);
      transition: all 0.2s ease;
    }

    h1, h2, h3 {
      font-weight: 700;
      color: var(--text-dark);
      line-height: 1.3;
      letter-spacing: -0.3px;
    }

    h1 { font-size: 42px; line-height: 1.2; margin-bottom: 0.3em; }
    h2 { font-size: 32px; margin-bottom: 0.5em; }
    h3 { font-size: 20px; margin-bottom: 0.4em; }

    .container {
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 24px;
      width: 100%;
    }

    /* ----- 导航 (白底固定) ----- */
    header.main-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--nav-height);
      background: var(--white);
      border-bottom: 1px solid var(--border-light);
      z-index: 1000;
      display: flex;
      align-items: center;
      backdrop-filter: blur(4px);
    }

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

    .logo {
      font-size: 24px;
      font-weight: 700;
      color: var(--dark-indigo);
      letter-spacing: 0.5px;
      white-space: nowrap;
    }
    .logo span {
      color: var(--primary-red);
    }

    .nav-menu {
      display: flex;
      align-items: center;
      gap: 32px;
    }

    .nav-link {
      font-size: 15px;
      font-weight: 500;
      color: var(--text-mid);
      padding: 6px 0;
      border-bottom: 2px solid transparent;
      transition: color 0.2s, border-color 0.2s;
    }
    .nav-link:hover, .nav-link.active {
      color: var(--primary-red);
      border-bottom-color: var(--primary-red);
    }

    .btn-cta-nav {
      background: var(--primary-red);
      color: white;
      padding: 12px 28px;
      font-size: 15px;
      font-weight: 600;
      margin-left: 16px;
      white-space: nowrap;
    }
    .btn-cta-nav:hover {
      background: var(--primary-red-hover);
    }

    /* 汉堡菜单 */
    .hamburger {
      display: none;
      font-size: 28px;
      background: none;
      border: none;
      color: var(--dark-indigo);
      width: 40px;
      height: 40px;
    }

    .mobile-menu-overlay {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background: var(--dark-indigo);
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 28px;
      z-index: 999;
    }
    .mobile-menu-overlay .nav-link {
      color: white;
      font-size: 22px;
      border: none;
    }
    .mobile-menu-overlay .btn-cta-nav {
      background: white;
      color: var(--primary-red);
      margin-left: 0;
    }

    /* 按钮体系 */
    .btn-primary {
      background: var(--primary-red);
      color: white;
      padding: 14px 32px;
      font-weight: 600;
      border-radius: var(--radius-btn);
    }
    .btn-primary:hover { background: var(--primary-red-hover); }

    .btn-secondary {
      background: transparent;
      color: var(--primary-red);
      padding: 14px 32px;
      font-weight: 600;
      border: 1px solid var(--primary-red);
      border-radius: var(--radius-btn);
    }
    .btn-secondary:hover {
      background: var(--primary-red-light);
    }

    .section {
      padding: 100px 0;
    }

    /* 英雄区 */
    .hero {
      min-height: 90vh;
      display: flex;
      align-items: center;
      background: var(--bg-light);
      margin-top: var(--nav-height);
      position: relative;
      overflow: hidden;
    }
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 40px;
      align-items: center;
    }
    .hero-text h1 {
      font-size: 48px;
      line-height: 1.1;
    }
    .hero-text h1 span {
      color: var(--primary-red);
    }
    .hero-desc {
      font-size: 18px;
      color: var(--text-gray);
      margin: 24px 0 32px;
      max-width: 500px;
    }
    .hero-actions {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    .hero-image img {
      border-radius: 20px;
      filter: drop-shadow(0 10px 20px rgba(0,0,0,0.15));
    }
    .scroll-indicator {
      position: absolute;
      bottom: 30px;
      left: 50%;
      transform: translateX(-50%);
      font-size: 24px;
      color: var(--primary-red);
      animation: bounce 2s infinite;
    }

    /* 区塊标题 */
    .section-header {
      text-align: center;
      margin-bottom: 60px;
    }
    .amber-highlight {
      color: var(--accent-amber);
      font-weight: 700;
    }

    /* 特色网格 */
    .features-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 24px;
    }
    .feature-card {
      background: var(--white);
      padding: 32px;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      transition: all var(--transition);
      border: 1px solid transparent;
    }
    .feature-card:hover {
      box-shadow: var(--shadow-hover);
      transform: translateY(-4px);
      border-color: var(--primary-red);
    }
    .feature-icon {
      font-size: 38px;
      color: var(--primary-red);
      margin-bottom: 20px;
    }

    /* 流程 */
    .flow-steps {
      display: flex;
      justify-content: space-between;
      align-items: flex-start;
      position: relative;
      text-align: center;
      background: var(--bg-light);
      padding: 40px 24px;
      border-radius: 24px;
    }
    .step-item {
      flex: 1;
      position: relative;
    }
    .step-number {
      width: 48px;
      height: 48px;
      background: var(--primary-red);
      color: white;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      margin: 0 auto 16px;
      font-weight: 700;
      font-size: 22px;
    }
    .flow-steps::before {
      content: '';
      position: absolute;
      top: 24px;
      left: 12%;
      width: 76%;
      height: 2px;
      border-top: 2px dashed var(--primary-red-light);
      z-index: 0;
    }

    /* 案例网格 (瀑布流感) */
    .cases-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
      align-items: start;
    }
    .case-card {
      background: white;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      overflow: hidden;
      transition: var(--transition);
    }
    .case-card:hover {
      box-shadow: var(--shadow-hover);
    }
    .case-cover {
      position: relative;
      overflow: hidden;
    }
    .case-cover img {
      width: 100%;
      aspect-ratio: 4 / 3;
      object-fit: cover;
      border-radius: var(--radius-card) var(--radius-card) 0 0;
      transition: transform 0.4s ease;
    }
    .case-card:hover .case-cover img {
      transform: scale(1.05);
    }
    .case-content {
      padding: 20px;
    }
    .case-metric {
      font-size: 28px;
      font-weight: 700;
      color: var(--accent-amber);
      margin: 12px 0 4px;
    }

    /* FAQ */
    .faq-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 16px;
    }
    .faq-item {
      background: white;
      border-radius: var(--radius-card);
      padding: 0 24px;
      border: 1px solid var(--border-light);
    }
    details summary {
      list-style: none;
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 56px;
      cursor: pointer;
      font-weight: 600;
      color: var(--text-dark);
    }
    details[open] summary {
      color: var(--primary-red);
    }
    details .faq-content {
      padding: 0 0 20px;
      background: var(--bg-expand);
      margin: 0 -24px;
      padding: 16px 24px;
    }

    /* 深色CTA */
    .dark-cta {
      background: var(--dark-indigo);
      text-align: center;
      padding: 100px 0;
      color: white;
    }

    /* Footer */
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1.5fr;
      gap: 40px;
    }
    footer {
      background: var(--dark-indigo);
      color: var(--text-footer);
      padding: 60px 0 30px;
    }
    .footer-heading {
      color: white;
      font-weight: 600;
      margin-bottom: 20px;
    }

    @keyframes bounce{ 0%,100%{transform:translateX(-50%) translateY(0);} 50%{transform:translateX(-50%) translateY(8px);} }

    /* 响应式 */
    @media (max-width: 1024px) {
      .features-grid { grid-template-columns: repeat(2, 1fr); }
      .cases-grid { grid-template-columns: 1fr 1fr; }
    }
    @media (max-width: 768px) {
      .hamburger { display: flex; }
      .nav-menu { display: none; }
      .hero-grid { grid-template-columns: 1fr; }
      .hero-image { order: -1; }
      h1 { font-size: 32px; }
      .features-grid, .cases-grid, .faq-grid { grid-template-columns: 1fr; }
      .flow-steps { flex-direction: column; gap: 24px; }
      .flow-steps::before { display: none; }
      .footer-grid { grid-template-columns: 1fr; }
    }