/* roulang page: index */
:root {
      --deep-slate: #2B2D35;
      --electric-cyan: #0AE5C0;
      --cyan-hover: #0AC5A8;
      --bg-light: #F7F8FA;
      --white: #FFFFFF;
      --text-primary: #2B2D35;
      --text-secondary: #6B7280;
      --text-muted: #4B5563;
      --border-light: #E5E7EB;
      --shadow-card: 0 4px 20px rgba(0,0,0,0.04);
      --shadow-hover: 0 12px 32px rgba(0,0,0,0.08);
      --radius-card: 12px;
      --radius-btn: 8px;
      --nav-width: 240px;
      --header-height: 64px;
      --section-gap: 120px;
      --font-sans: 'Inter', 'PingFang SC', 'Microsoft YaHei', 'Hiragino Sans GB', system-ui, -apple-system, sans-serif;
      --transition-smooth: 0.25s ease;
      --transition-btn: 0.2s ease;
    }

    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }

    html {
      scroll-behavior: smooth;
      font-size: 16px;
    }

    body {
      font-family: var(--font-sans);
      background-color: var(--bg-light);
      color: var(--text-primary);
      line-height: 1.7;
      display: flex;
      min-height: 100vh;
    }

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

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

    button, .btn {
      cursor: pointer;
      font-family: inherit;
      transition: all var(--transition-btn);
      display: inline-flex;
      align-items: center;
      justify-content: center;
      border: none;
      outline: none;
      font-weight: 600;
      border-radius: var(--radius-btn);
      padding: 14px 32px;
      font-size: 1rem;
    }

    .btn-primary {
      background-color: var(--electric-cyan);
      color: var(--deep-slate);
    }
    .btn-primary:hover {
      background-color: var(--cyan-hover);
      transform: scale(1.03);
    }

    .btn-secondary {
      background: transparent;
      border: 1.5px solid var(--deep-slate);
      color: var(--deep-slate);
    }
    .btn-secondary:hover {
      background-color: var(--deep-slate);
      color: var(--white);
      transform: scale(1.03);
    }

    .btn-white {
      background: var(--white);
      color: var(--deep-slate);
      font-weight: 600;
      border-radius: var(--radius-btn);
      padding: 14px 32px;
    }
    .btn-white:hover {
      background-color: #e5e7eb;
      transform: scale(1.03);
    }

    /* 桌面端左侧竖向导航 */
    .desktop-nav {
      position: fixed;
      top: 0;
      left: 0;
      width: var(--nav-width);
      height: 100vh;
      background-color: var(--deep-slate);
      color: var(--white);
      display: flex;
      flex-direction: column;
      padding: 40px 24px;
      z-index: 100;
    }

    .logo-area {
      margin-bottom: 60px;
    }
    .logo {
      font-size: 28px;
      font-weight: 700;
      letter-spacing: 2px;
      color: var(--white);
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .logo-icon {
      width: 32px;
      height: 32px;
      background: var(--electric-cyan);
      border-radius: 8px;
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--deep-slate);
      font-weight: 700;
      font-size: 20px;
    }

    .nav-links {
      list-style: none;
      display: flex;
      flex-direction: column;
      gap: 20px;
    }
    .nav-links a {
      color: #D1D5DB;
      font-weight: 500;
      font-size: 1rem;
      padding: 8px 12px;
      border-left: 2px solid transparent;
      transition: all var(--transition-smooth);
      display: block;
    }
    .nav-links a:hover {
      color: var(--electric-cyan);
      border-left-color: var(--electric-cyan);
    }

    /* 移动端汉堡菜单 (默认隐藏) */
    .mobile-header {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--header-height);
      background: var(--deep-slate);
      color: white;
      align-items: center;
      justify-content: space-between;
      padding: 0 20px;
      z-index: 110;
    }
    .hamburger {
      font-size: 28px;
      background: none;
      border: none;
      color: white;
      padding: 8px;
    }
    .mobile-menu-overlay {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background: var(--deep-slate);
      z-index: 105;
      flex-direction: column;
      justify-content: center;
      align-items: center;
      gap: 32px;
    }
    .mobile-menu-overlay a {
      color: white;
      font-size: 1.5rem;
      font-weight: 500;
    }

    /* 右侧主内容区 */
    .main-content {
      margin-left: var(--nav-width);
      flex: 1;
      width: calc(100% - var(--nav-width));
    }

    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 32px;
    }

    section {
      padding: 100px 0;
    }

    /* Hero */
    #hero {
      display: flex;
      align-items: center;
      min-height: 100vh;
      background-color: var(--white);
      padding-top: 0;
    }
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 60px;
      align-items: center;
    }
    .hero-text h1 {
      font-size: clamp(2.5rem, 5vw, 3.5rem);
      font-weight: 700;
      line-height: 1.2;
      margin-bottom: 24px;
      color: var(--deep-slate);
    }
    .hero-text .sub {
      font-size: 1.125rem;
      color: var(--text-secondary);
      margin-bottom: 32px;
      max-width: 480px;
    }
    .cta-group {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    .hero-visual {
      background: #F0F2F5;
      border-radius: 32px;
      padding: 40px;
      display: flex;
      align-items: center;
      justify-content: center;
      position: relative;
      overflow: hidden;
    }
    .hero-visual img {
      border-radius: 20px;
      width: 100%;
      height: auto;
    }

    /* 标题动画 */
    .fade-up span {
      display: inline-block;
      opacity: 0;
      transform: translateY(20px);
      animation: fadeUpWord 0.5s forwards;
    }
    @keyframes fadeUpWord {
      to { opacity: 1; transform: translateY(0); }
    }

    h2 {
      font-size: 2.25rem;
      font-weight: 600;
      margin-bottom: 16px;
    }
    .section-sub {
      color: var(--text-secondary);
      margin-bottom: 48px;
      font-size: 1.125rem;
    }

    /* 能力卡片错位网格 */
    .capabilities-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .cap-card {
      background: var(--white);
      border-radius: var(--radius-card);
      padding: 32px;
      box-shadow: var(--shadow-card);
      transition: all var(--transition-smooth);
      display: flex;
      flex-direction: column;
    }
    .cap-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
    }
    .cap-card.large {
      grid-row: span 2;
    }
    .icon-placeholder {
      width: 48px;
      height: 48px;
      background: #E0F7F4;
      border-radius: 12px;
      display: flex;
      align-items: center;
      justify-content: center;
      margin-bottom: 24px;
      color: var(--electric-cyan);
      font-size: 24px;
    }
    .cap-card h3 {
      font-size: 1.5rem;
      margin-bottom: 12px;
    }

    /* 场景交替 */
    .scenario-row {
      display: flex;
      align-items: center;
      gap: 80px;
      margin-bottom: 80px;
    }
    .scenario-row.reverse {
      flex-direction: row-reverse;
    }
    .scenario-img {
      flex: 1;
      background: #E5E7EB;
      border-radius: 24px;
      overflow: hidden;
    }
    .scenario-img img {
      width: 100%;
      height: auto;
    }
    .scenario-text {
      flex: 1;
    }

    /* 案例卡片 */
    .cases-scroll {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .case-card {
      background: #F2F4F7;
      border-radius: var(--radius-card);
      padding: 32px;
      transition: var(--transition-smooth);
    }
    .case-tag {
      background: var(--deep-slate);
      color: white;
      padding: 4px 12px;
      border-radius: 20px;
      font-size: 0.8rem;
      display: inline-block;
      margin-bottom: 16px;
    }
    .case-number {
      font-size: 2rem;
      font-weight: 700;
      color: var(--deep-slate);
    }

    /* 价格卡片 */
    .pricing-grid {
      display: flex;
      justify-content: center;
      gap: 24px;
      flex-wrap: wrap;
    }
    .pricing-card {
      background: white;
      border-radius: var(--radius-card);
      padding: 40px 32px;
      box-shadow: var(--shadow-card);
      flex: 1;
      min-width: 250px;
      max-width: 300px;
      text-align: center;
      border: 1px solid transparent;
    }
    .pricing-card.featured {
      border-color: var(--electric-cyan);
      box-shadow: 0 8px 30px rgba(10,229,192,0.15);
    }

    /* FAQ */
    .faq-list {
      background: #F2F4F7;
      border-radius: 20px;
      padding: 32px;
    }
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 20px 0;
    }
    .faq-question {
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      cursor: pointer;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease;
      color: var(--text-muted);
    }
    .faq-item.open .faq-answer {
      max-height: 200px;
      padding-top: 16px;
    }

    /* CTA 横幅 */
    .cta-banner {
      background: var(--deep-slate);
      border-radius: 32px;
      padding: 80px 40px;
      text-align: center;
      color: white;
    }

    /* Footer */
    .footer {
      background: var(--deep-slate);
      color: #D1D5DB;
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr;
      gap: 40px;
    }
    .copyright {
      border-top: 1px solid #4B5563;
      margin-top: 40px;
      padding-top: 20px;
      text-align: center;
      font-size: 0.9rem;
    }

    @media (max-width: 1024px) {
      .capabilities-grid { grid-template-columns: repeat(2,1fr); }
      .cases-scroll { grid-template-columns: 1fr 1fr; }
    }
    @media (max-width: 768px) {
      .desktop-nav { display: none; }
      .mobile-header { display: flex; }
      .main-content { margin-left: 0; width: 100%; }
      .hero-grid { grid-template-columns: 1fr; }
      .capabilities-grid { grid-template-columns: 1fr; }
      .scenario-row, .scenario-row.reverse { flex-direction: column; }
      .cases-scroll { grid-template-columns: 1fr; }
      .footer-grid { grid-template-columns: 1fr; }
      section { padding: 70px 0; }
    }