/* roulang page: index */
:root {
      --primary: #4E6EF2;
      --primary-dark: #3A5AD9;
      --primary-soft: rgba(78,110,242,0.08);
      --success: #00B578;
      --warning: #FF9F0A;
      --danger: #FA5151;
      --bg: #F5F6FA;
      --card: #FFFFFF;
      --dark-bg: #1F2329;
      --text-main: #1F2329;
      --text-secondary: #86909C;
      --text-white: #FFFFFF;
      --text-placeholder: #C0C4CC;
      --border-light: #E8EAEF;
      --radius-sm: 8px;
      --radius-md: 12px;
      --radius-lg: 20px;
      --shadow-card: 0 4px 16px rgba(0,0,0,0.04);
      --shadow-nav: 0 1px 0 rgba(0,0,0,0.05);
      --shadow-elevated: 0 8px 24px rgba(0,0,0,0.06);
      --font-system: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --transition: 200ms ease-in-out;
      --max-width: 1200px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    html {
      scroll-behavior: smooth;
    }
    body {
      font-family: var(--font-system);
      font-size: 16px;
      line-height: 1.5;
      color: var(--text-main);
      background-color: var(--bg);
      min-height: 100vh;
    }
    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: color var(--transition);
    }
    button, .btn {
      cursor: pointer;
      font-family: var(--font-system);
      border: none;
      background: none;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      font-weight: 500;
      transition: all var(--transition);
      border-radius: var(--radius-sm);
    }
    ul {
      list-style: none;
    }
    h1, h2, h3, h4 {
      font-weight: 600;
      line-height: 1.3;
    }
    h1 { font-size: 40px; }
    h2 { font-size: 32px; }
    h3 { font-size: 24px; }
    h4 { font-size: 20px; }
    .section {
      padding: 80px 0;
    }
    /* 导航 */
    .nav {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 64px;
      background: rgba(255,255,255,0.92);
      backdrop-filter: blur(12px);
      box-shadow: var(--shadow-nav);
      z-index: 100;
      display: flex;
      align-items: center;
      transition: box-shadow var(--transition);
    }
    .nav.scrolled {
      box-shadow: 0 2px 20px rgba(0,0,0,0.06);
    }
    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }
    .logo {
      display: flex;
      align-items: center;
      gap: 8px;
      font-weight: 700;
      font-size: 22px;
      color: var(--primary);
    }
    .logo-icon {
      width: 28px;
      height: 28px;
      background: var(--primary);
      border-radius: 6px;
      display: flex;
      align-items: center;
      justify-content: center;
      color: white;
      font-size: 18px;
      font-weight: 700;
    }
    .nav-links {
      display: flex;
      gap: 32px;
      align-items: center;
    }
    .nav-links a {
      font-size: 15px;
      color: var(--text-main);
      font-weight: 500;
      position: relative;
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--primary);
      transition: width var(--transition);
    }
    .nav-links a:hover { color: var(--primary); }
    .nav-links a:hover::after { width: 100%; }
    .btn-primary {
      background: var(--primary);
      color: white;
      padding: 10px 24px;
      border-radius: var(--radius-sm);
      font-weight: 500;
      box-shadow: 0 2px 8px rgba(78,110,242,0.2);
    }
    .btn-primary:hover { background: var(--primary-dark); }
    .btn-outline {
      border: 1px solid var(--primary);
 color: var(--primary);
      padding: 10px 24px;
      background: transparent;
    }
    .btn-outline:hover { background: var(--primary-soft); }
    .menu-toggle {
      display: none;
      flex-direction: column;
      gap: 5px;
      background: none;
      border: none;
      width: 28px;
    }
    .menu-toggle span {
      height: 2px;
      background: var(--text-main);
      border-radius: 2px;
      transition: var(--transition);
    }
    /* 移动端导航 */
    @media (max-width: 768px) {
      .nav-links {
        position: fixed;
        top: 64px;
        left: 0;
        width: 100%;
        background: white;
        flex-direction: column;
        padding: 24px;
        gap: 20px;
        box-shadow: 0 10px 25px rgba(0,0,0,0.08);
        transform: translateY(-120%);
        transition: transform 0.3s ease;
        z-index: 99;
      }
      .nav-links.active {
        transform: translateY(0);
      }
      .menu-toggle { display: flex; }
    }
    /* Hero */
    .hero {
      padding: 120px 0 80px;
      background: linear-gradient(180deg, #F5F6FA 0%, #FFFFFF 100%);
    }
    .hero-grid {
      display: flex;
      align-items: center;
      gap: 48px;
    }
    .hero-text {
      flex: 1 1 55%;
    }
    .hero-image {
      flex: 1 1 45%;
      text-align: center;
    }
    .hero-image img {
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-elevated);
    }
    .hero h1 {
      margin-bottom: 20px;
    }
    .hero p {
      font-size: 18px;
      color: var(--text-secondary);
      margin-bottom: 32px;
      max-width: 560px;
    }
    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    @media (max-width: 768px) {
      .hero-grid { flex-direction: column; }
      .hero-text { text-align: center; }
      .hero p { margin-left: auto; margin-right: auto; }
      .hero-buttons { justify-content: center; }
      h1 { font-size: 32px; }
      h2 { font-size: 26px; }
    }
    /* 卡片通用 */
    .card {
      background: var(--card);
      border-radius: var(--radius-md);
      box-shadow: var(--shadow-card);
      padding: 24px;
      transition: transform var(--transition), box-shadow var(--transition);
    }
    .card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-elevated);
    }
    .grid-2, .grid-3, .grid-4 {
      display: grid;
      gap: 24px;
    }
    .grid-2 { grid-template-columns: repeat(2,1fr); }
    .grid-3 { grid-template-columns: repeat(3,1fr); }
    .grid-4 { grid-template-columns: repeat(4,1fr); }
    @media (max-width: 1024px) {
      .grid-3, .grid-4 { grid-template-columns: repeat(2,1fr); }
    }
    @media (max-width: 640px) {
      .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
    }
    .section-title {
      text-align: center;
      margin-bottom: 48px;
    }
    .section-title h2 { margin-bottom: 12px; }
    .section-title p { color: var(--text-secondary); max-width: 640px; margin: 0 auto; }
    /* 痛点 */
    .pain-card {
      border-left: 4px solid var(--primary);
      padding-left: 20px;
    }
    /* 解决方案卡片 */
    .solution-card img {
      border-radius: var(--radius-md);
      margin-bottom: 16px;
      height: 180px;
      object-fit: cover;
      width: 100%;
    }
    /* 优势 */
    .advantage-row {
      display: flex;
      gap: 48px;
      align-items: center;
    }
    .advantage-list {
      flex: 1;
      display: flex;
      flex-direction: column;
      gap: 28px;
    }
    .advantage-item {
      display: flex;
      gap: 16px;
      align-items: flex-start;
    }
    .advantage-icon {
      width: 44px;
      height: 44px;
      background: var(--primary-soft);
      border-radius: 12px;
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--primary);
      font-size: 22px;
    }
    .advantage-panel {
      flex: 1;
      background: var(--card);
      border-radius: var(--radius-lg);
      padding: 24px;
      box-shadow: var(--shadow-card);
    }
    @media (max-width: 768px) { .advantage-row { flex-direction: column; } }
    /* 数据 */
    .metric-badge {
      background: white;
      border-radius: var(--radius-md);
      padding: 20px 16px;
      text-align: center;
      box-shadow: var(--shadow-card);
    }
    .metric-number {
      font-size: 32px;
      font-weight: 700;
      color: var(--primary);
    }
    /* 证言 */
    .testimonial-card {
      background: var(--card);
      border-radius: var(--radius-md);
      padding: 24px;
      display: flex;
      gap: 16px;
    }
    .avatar-placeholder {
      width: 48px;
      height: 48px;
      background: #E8EAEF;
      border-radius: 50%;
    }
    /* 流程 */
    .process-steps {
      display: flex;
      justify-content: space-between;
      position: relative;
    }
    .step {
      text-align: center;
      flex: 1;
    }
    .step-circle {
      width: 40px;
      height: 40px;
      background: var(--primary);
      color: white;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      margin: 0 auto 12px;
      font-weight: 700;
    }
    @media (max-width: 768px) { .process-steps { flex-direction: column; gap: 24px; } }
    /* FAQ */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 16px 0;
    }
    .faq-question {
      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;
      color: var(--text-secondary);
    }
    .faq-item.open .faq-answer {
      max-height: 150px;
      margin-top: 12px;
    }
    /* CTA深色 */
    .cta-dark {
      background: var(--dark-bg);
      color: white;
      text-align: center;
      padding: 80px 24px;
      border-radius: var(--radius-lg);
      margin: 40px 0;
    }
    .cta-dark h2 { color: white; }
    .footer {
      background: var(--dark-bg);
      color: var(--text-secondary);
      padding: 48px 0 24px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: repeat(4,1fr);
      gap: 24px;
      margin-bottom: 32px;
    }
    .footer h4 { color: white; margin-bottom: 16px; }
    .footer a { color: var(--text-secondary); font-size: 14px; display: block; margin-bottom: 8px; }
    .footer a:hover { color: var(--primary); }
    .footer-bottom {
      border-top: 1px solid rgba(255,255,255,0.1);
      padding-top: 20px;
      display: flex;
      justify-content: space-between;
    }
    @media (max-width: 768px) {
      .footer-grid { grid-template-columns: repeat(2,1fr); }
      .footer-bottom { flex-direction: column; gap: 8px; text-align: center; }
    }