/* roulang page: index */
:root {
      --color-primary: #E53935;
      --color-primary-dark: #C62828;
      --color-secondary: #1A1A2E;
      --color-accent: #FFB300;
      --color-bg: #FAFAFA;
      --color-card: #FFFFFF;
      --color-text: #333333;
      --color-text-light: #666666;
      --color-text-lighter: #999999;
      --color-border: #E0E0E0;
      --font-heading: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", system-ui, sans-serif;
      --font-body: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", system-ui, sans-serif;
      --font-number: "Inter", "Poppins", system-ui, sans-serif;
      --radius-lg: 12px;
      --radius-md: 8px;
      --radius-pill: 50px;
      --shadow-card: 0 4px 20px rgba(0,0,0,0.06);
      --shadow-hover: 0 8px 30px rgba(0,0,0,0.12);
      --transition: 0.2s ease;
      --container-max: 1200px;
      --nav-height: 72px;
      --nav-height-mobile: 60px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    html {
      scroll-behavior: smooth;
    }
    body {
      font-family: var(--font-body);
      background-color: var(--color-bg);
      color: var(--color-text);
      line-height: 1.75;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
      overflow-x: hidden;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: var(--transition);
    }
    ul {
      list-style: none;
    }
    .container {
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 24px;
    }
    /* 导航 */
    .navbar {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 1000;
      height: var(--nav-height);
      display: flex;
      align-items: center;
      transition: background-color 0.3s ease, box-shadow 0.3s ease, color 0.3s ease;
      background-color: transparent;
      color: white;
    }
    .navbar.scrolled {
      background-color: white;
      color: var(--color-text);
      box-shadow: 0 4px 20px rgba(0,0,0,0.04);
    }
    .navbar .container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
    }
    .logo {
      display: flex;
      align-items: center;
      gap: 8px;
      font-weight: 700;
      font-size: 1.4rem;
      color: inherit;
      font-family: var(--font-heading);
      letter-spacing: -0.3px;
    }
    .logo svg {
      width: 28px;
      height: 28px;
      fill: currentColor;
    }
    .nav-links {
      display: flex;
      gap: 32px;
      align-items: center;
      font-weight: 500;
      font-size: 0.95rem;
    }
    .nav-links a {
      position: relative;
      padding: 4px 0;
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: -2px;
      left: 0;
      width: 0;
      height: 2px;
      background-color: var(--color-primary);
      transition: width 0.2s ease;
    }
    .nav-links a:hover::after {
      width: 100%;
    }
    .nav-cta {
      background-color: var(--color-accent);
      color: #1A1A2E !important;
      padding: 10px 24px;
      border-radius: var(--radius-pill);
      font-weight: 700;
      font-size: 0.9rem;
      letter-spacing: 0.3px;
      box-shadow: 0 2px 8px rgba(255,179,0,0.3);
      transition: 0.2s;
    }
    .nav-cta:hover {
      background-color: #FFA000;
      transform: scale(1.02);
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: transparent;
      border: none;
      padding: 8px;
    }
    .hamburger span {
      width: 24px;
      height: 2px;
      background: currentColor;
      transition: 0.3s;
    }
    .mobile-menu {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100vh;
      background: var(--color-secondary);
      color: white;
      flex-direction: column;
      justify-content: center;
      align-items: center;
      gap: 32px;
      font-size: 1.4rem;
      z-index: 999;
      transform: translateY(-100%);
      transition: transform 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    }
    .mobile-menu.active {
      transform: translateY(0);
    }
    .mobile-menu a {
      color: white;
      font-weight: 600;
    }
    /* Hero */
    .hero {
      background: var(--color-secondary);
      color: white;
      min-height: 100vh;
      display: flex;
      align-items: center;
      position: relative;
      overflow: hidden;
      padding-top: var(--nav-height);
    }
    .hero::before {
      content: '';
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background: radial-gradient(circle at 30% 40%, rgba(229,57,53,0.15) 0%, transparent 50%);
      pointer-events: none;
    }
    .hero .container {
      display: flex;
      align-items: center;
      gap: 48px;
      position: relative;
      z-index: 2;
      width: 100%;
    }
    .hero-text {
      flex: 1 1 50%;
    }
    .hero-text h1 {
      font-size: 3.2rem;
      font-weight: 700;
      line-height: 1.2;
      margin-bottom: 20px;
      letter-spacing: -0.5px;
    }
    .hero-text .sub {
      font-size: 1.2rem;
      opacity: 0.85;
      margin-bottom: 32px;
      max-width: 450px;
    }
    .hero-buttons {
      display: flex;
      gap: 20px;
      flex-wrap: wrap;
    }
    .btn-primary {
      background: var(--color-primary);
      color: white;
      padding: 14px 32px;
      border-radius: var(--radius-md);
      font-weight: 600;
      border: none;
      cursor: pointer;
      transition: 0.2s;
      display: inline-block;
    }
    .btn-primary:hover {
      background: var(--color-primary-dark);
    }
    .btn-outline {
      background: transparent;
      border: 2px solid white;
      color: white;
      padding: 14px 32px;
      border-radius: var(--radius-md);
      font-weight: 600;
      transition: 0.2s;
    }
    .btn-outline:hover {
      background: rgba(255,255,255,0.1);
    }
    .hero-image {
      flex: 1 1 50%;
      display: flex;
      justify-content: center;
      position: relative;
    }
    .hero-image img {
      max-height: 500px;
      border-radius: 24px;
      box-shadow: 0 25px 50px rgba(0,0,0,0.4);
    }
    .hero-accent {
      position: absolute;
      width: 220px;
      height: 220px;
      border: 2px solid var(--color-accent);
      border-radius: 50%;
      top: 20%;
      right: 10%;
      opacity: 0.2;
      animation: pulse 3s infinite;
    }
    @keyframes pulse {
      0% { transform: scale(0.95); opacity: 0.15; }
      50% { transform: scale(1.05); opacity: 0.25; }
      100% { transform: scale(0.95); opacity: 0.15; }
    }
    section {
      padding: 90px 0;
    }
    .section-title {
      font-size: 2.2rem;
      font-weight: 700;
      margin-bottom: 16px;
      text-align: center;
    }
    .section-sub {
      text-align: center;
      color: var(--color-text-light);
      margin-bottom: 48px;
    }
    /* 服务非对称网格 */
    .services-grid {
      display: grid;
      grid-template-columns: 2fr 1fr;
      gap: 24px;
      margin-top: 20px;
    }
    .service-card {
      background: var(--color-card);
      border-radius: var(--radius-lg);
      padding: 28px;
      box-shadow: var(--shadow-card);
      transition: var(--transition);
      display: flex;
      align-items: center;
      gap: 20px;
      border-left: 4px solid transparent;
    }
    .service-card.large {
      border-left-color: var(--color-primary);
      background: #fafafa;
    }
    .service-card:hover {
      box-shadow: var(--shadow-hover);
      transform: translateY(-4px);
    }
    .service-icon {
      width: 56px;
      height: 56px;
      background: var(--color-primary);
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      color: white;
      font-size: 24px;
    }
    .service-content h3 {
      font-size: 1.4rem;
      margin-bottom: 6px;
    }
    .second-row {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 24px;
      margin-top: 24px;
    }
    /* 数据深色区 */
    .stats {
      background: var(--color-secondary);
      color: white;
    }
    .stats-grid {
      display: flex;
      justify-content: space-around;
      flex-wrap: wrap;
      text-align: center;
    }
    .stat-item {
      flex: 1;
      min-width: 140px;
    }
    .stat-number {
      font-family: var(--font-number);
      font-size: 3.2rem;
      font-weight: 800;
      color: var(--color-accent);
    }
    /* 案例错位 */
    .cases-flow {
      display: flex;
      flex-direction: column;
      gap: 40px;
      margin-top: 30px;
    }
    .case-card {
      width: 65%;
      background-size: cover;
      background-position: center;
      border-radius: var(--radius-lg);
      height: 280px;
      position: relative;
      overflow: hidden;
      transition: 0.3s;
    }
    .case-card:nth-child(even) {
      align-self: flex-end;
    }
    .case-card:hover {
      transform: scale(1.02);
    }
    .case-overlay {
      position: absolute;
      bottom: 0;
      width: 100%;
      padding: 24px;
      background: linear-gradient(transparent, rgba(0,0,0,0.8));
      color: white;
    }
    /* 方案交替 */
    .solution-row {
      display: flex;
      align-items: center;
      gap: 48px;
      margin-bottom: 60px;
    }
    .solution-row.reverse {
      flex-direction: row-reverse;
    }
    .solution-img {
      flex: 1;
      border-radius: var(--radius-lg);
      overflow: hidden;
    }
    .solution-text {
      flex: 1;
    }
    .solution-text h3 {
      font-size: 1.8rem;
      margin-bottom: 16px;
    }
    /* FAQ */
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }
    .faq-item {
      background: white;
      border: 1px solid var(--color-border);
      border-radius: var(--radius-md);
      margin-bottom: 12px;
      overflow: hidden;
    }
    .faq-question {
      padding: 20px;
      font-weight: 600;
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      padding: 0 20px;
      color: #555;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-bottom: 20px;
    }
    .faq-item.active {
      border-left: 4px solid var(--color-primary);
    }
    /* CTA横幅 */
    .cta-banner {
      background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
      color: white;
      text-align: center;
      padding: 80px 0;
    }
    .footer {
      background: var(--color-secondary);
      color: rgba(255,255,255,0.8);
      padding: 50px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 30px;
    }
    @media (max-width: 992px) {
      .hero .container { flex-direction: column; text-align: center; }
      .hero-text h1 { font-size: 2.5rem; }
      .services-grid { grid-template-columns: 1fr; }
      .second-row { grid-template-columns: 1fr; }
      .case-card { width: 100%; }
      .solution-row, .solution-row.reverse { flex-direction: column; }
    }
    @media (max-width: 768px) {
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .mobile-menu { display: flex; }
      .footer-grid { grid-template-columns: 1fr 1fr; }
      .stats-grid { gap: 20px; }
    }