/* roulang page: index */
:root {
      --primary: #0A6EFF;
      --primary-dark: #0857CC;
      --accent-orange: #FF6B2B;
      --accent-orange-dark: #E55A1F;
      --gold: #F5A623;
      --deep-bg: #0B1E3C;
      --text-dark: #1E293B;
      --text-body: #475569;
      --text-muted: #64748B;
      --bg-page: #F8FAFC;
      --bg-white: #FFFFFF;
      --bg-light: #F1F5F9;
      --border-light: #E2E8F0;
      --shadow-sm: 0 4px 16px rgba(0,0,0,0.04);
      --shadow-md: 0 8px 24px rgba(0,0,0,0.08);
      --shadow-hover: 0 12px 28px rgba(0,0,0,0.12);
      --radius-md: 12px;
      --radius-btn: 8px;
      --transition: 0.25s ease;
      --font-title: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
      --font-body: 'PingFang SC', 'Microsoft YaHei', 'Segoe UI', sans-serif;
      --max-width: 1200px;
      --section-gap: 100px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    body {
      font-family: var(--font-body);
      background-color: var(--bg-page);
      color: var(--text-body);
      line-height: 1.7;
      font-size: 1rem;
      -webkit-font-smoothing: antialiased;
    }
    a {
      text-decoration: none;
      color: inherit;
    }
    img {
      max-width: 100%;
      display: block;
    }
    button, input, textarea {
      font-family: inherit;
      outline: none;
    }
    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
      width: 100%;
    }
    /* header & nav */
    #header {
      position: sticky;
      top: 0;
      z-index: 50;
      background: var(--bg-white);
      border-bottom: 1px solid rgba(0,0,0,0.05);
      transition: box-shadow 0.3s;
    }
    #header.scrolled {
      box-shadow: var(--shadow-sm);
    }
    .nav-bar {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 72px;
    }
    .logo {
      display: flex;
      align-items: center;
      gap: 8px;
      font-weight: 700;
      font-size: 1.5rem;
      color: var(--text-dark);
      font-family: var(--font-title);
    }
    .logo i {
      color: var(--primary);
      font-size: 2rem;
    }
    .nav-links {
      display: flex;
      gap: 32px;
      align-items: center;
    }
    .nav-links a {
      font-size: 0.95rem;
      font-weight: 500;
      color: var(--text-body);
      transition: color var(--transition);
      position: relative;
      padding: 4px 0;
    }
    .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%;
    }
    .menu-toggle {
      display: none;
      background: none;
      border: none;
      font-size: 1.8rem;
      color: var(--text-dark);
      cursor: pointer;
    }
    /* mobile menu */
    @media (max-width: 768px) {
      .nav-links {
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100vh;
        background: white;
        flex-direction: column;
        justify-content: center;
        gap: 40px;
        transform: translateX(100%);
        transition: transform 0.35s ease;
        z-index: 60;
      }
      .nav-links.active {
        transform: translateX(0);
      }
      .menu-toggle {
        display: block;
        z-index: 70;
      }
    }
    /* hero */
    #hero {
      height: 100vh;
      min-height: 600px;
      background: linear-gradient(135deg, rgba(10,110,255,0.75) 0%, rgba(11,30,60,0.9) 100%), url('/assets/images/backpic/back-1.webp') center/cover no-repeat;
      display: flex;
      align-items: center;
      justify-content: center;
      text-align: center;
      color: white;
    }
    .hero-content h1 {
      font-size: 2.75rem;
      font-weight: 700;
      letter-spacing: -0.5px;
      color: white;
      font-family: var(--font-title);
      margin-bottom: 1.5rem;
    }
    .hero-content p {
      font-size: 1.25rem;
      margin-bottom: 2.5rem;
      opacity: 0.9;
    }
    .btn-group {
      display: flex;
      gap: 16px;
      justify-content: center;
      flex-wrap: wrap;
    }
    .btn {
      display: inline-block;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      transition: all 0.2s;
      cursor: pointer;
      font-size: 1rem;
      border: none;
    }
    .btn-primary {
      background: var(--primary);
      color: white;
    }
    .btn-primary:hover {
      background: var(--primary-dark);
      transform: translateY(-2px);
      box-shadow: 0 10px 20px rgba(10,110,255,0.3);
    }
    .btn-accent {
      background: var(--accent-orange);
      color: white;
    }
    .btn-accent:hover {
      background: var(--accent-orange-dark);
      transform: translateY(-2px);
      box-shadow: 0 10px 20px rgba(255,107,43,0.35);
    }
    .btn-outline {
      background: transparent;
      border: 2px solid white;
      color: white;
    }
    .btn-outline:hover {
      background: rgba(255,255,255,0.15);
    }
    section {
      padding: var(--section-gap) 0;
    }
    h2 {
      font-size: 2rem;
      font-weight: 600;
      color: var(--text-dark);
      font-family: var(--font-title);
      margin-bottom: 1rem;
    }
    h3 {
      font-size: 1.375rem;
      font-weight: 600;
      color: var(--text-dark);
    }
    .section-title {
      margin-bottom: 3rem;
    }
    /* pain points */
    .grid-3 {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .pain-card {
      background: var(--bg-white);
      padding: 32px 24px;
      border-radius: var(--radius-md);
      box-shadow: var(--shadow-sm);
      transition: all var(--transition);
    }
    .pain-card:hover {
      box-shadow: var(--shadow-hover);
      transform: translateY(-4px);
    }
    .pain-card i {
      font-size: 2rem;
      color: var(--primary);
      margin-bottom: 16px;
    }
    /* solution */
    .solution-row {
      display: flex;
      gap: 48px;
      align-items: flex-start;
    }
    .solution-left {
      flex: 1;
    }
    .solution-right {
      flex: 1;
      display: flex;
      flex-direction: column;
      gap: 28px;
    }
    .solution-item {
      display: flex;
      gap: 16px;
      align-items: flex-start;
      border-left: 3px solid var(--primary);
      padding-left: 20px;
    }
    /* results */
    .metrics {
      display: flex;
      justify-content: space-around;
      text-align: center;
      background: var(--bg-white);
      padding: 48px 24px;
      border-radius: var(--radius-md);
      box-shadow: var(--shadow-sm);
    }
    .metric-number {
      font-size: 3.5rem;
      font-weight: 700;
      color: var(--primary);
      line-height: 1.2;
    }
    /* testimonials */
    .testimonial-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 24px;
    }
    .testimonial-card {
      background: var(--bg-light);
      padding: 28px;
      border-radius: var(--radius-md);
      display: flex;
      gap: 20px;
      box-shadow: var(--shadow-sm);
    }
    .avatar {
      width: 48px;
      height: 48px;
      background: var(--primary);
      border-radius: 50%;
      background-image: url('/assets/images/coverpic/cover-1.webp');
      background-size: cover;
    }
    /* faq */
    .faq-item {
      background: var(--bg-white);
      border-radius: var(--radius-md);
      margin-bottom: 12px;
      box-shadow: var(--shadow-sm);
      border-left: 4px solid transparent;
      transition: 0.2s;
    }
    .faq-item.active {
      border-left-color: var(--primary);
      background: #F9FBFF;
    }
    .faq-question {
      padding: 20px 24px;
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
    }
    .faq-answer {
      padding: 0 24px 20px;
      display: none;
      color: var(--text-body);
    }
    .faq-item.active .faq-answer {
      display: block;
    }
    /* cta */
    #contact {
      background: var(--deep-bg);
      color: white;
    }
    .cta-inner {
      display: flex;
      gap: 40px;
      flex-wrap: wrap;
    }
    .cta-text {
      flex: 1;
    }
    .cta-form {
      flex: 1;
      background: rgba(255,255,255,0.08);
      padding: 32px;
      border-radius: var(--radius-md);
    }
    .form-group input, .form-group textarea {
      width: 100%;
      padding: 12px;
      margin-bottom: 16px;
      background: rgba(255,255,255,0.1);
      border: 1px solid rgba(255,255,255,0.2);
      border-radius: 6px;
      color: white;
    }
    .footer {
      background: #1E293B;
      color: #CBD5E1;
      padding: 48px 0 24px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 32px;
    }
    @media (max-width: 1024px) {
      .grid-3, .testimonial-grid { grid-template-columns: repeat(2,1fr); }
      .solution-row { flex-direction: column; }
    }
    @media (max-width: 768px) {
      h1 { font-size: 2rem; }
      .grid-3, .testimonial-grid, .footer-grid { grid-template-columns: 1fr; }
      .metrics { flex-direction: column; gap: 28px; }
      .nav-links { gap: 24px; }
    }