/* roulang page: index */
:root {
      --primary: #1A5F7A;
      --primary-deep: #134d63;
      --accent: #0D9488;
      --accent-hover: #0b7d72;
      --cta: #F59E0B;
      --cta-hover: #d98b0a;
      --bg: #F8FAFC;
      --card-bg: #FFFFFF;
      --text: #1E293B;
      --text-secondary: #64748B;
      --border: #E2E8F0;
      --shadow-sm: 0 1px 3px rgba(0,0,0,0.06), 0 4px 12px rgba(0,0,0,0.04);
      --shadow-hover: 0 6px 18px rgba(0,0,0,0.08), 0 2px 8px rgba(0,0,0,0.05);
      --radius-card: 12px;
      --radius-btn: 8px;
      --font-sans: 'Inter', 'PingFang SC', 'Microsoft YaHei', 'Hiragino Sans GB', sans-serif;
      --max-width: 1280px;
      --header-height: 72px;
      --ease: 0.25s ease;
      --transition-smooth: all .3s cubic-bezier(0.4, 0, 0.2, 1);
    }

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

    body {
      font-family: var(--font-sans);
      background-color: var(--bg);
      color: var(--text);
      line-height: 1.7;
      -webkit-font-smoothing: antialiased;
      scroll-behavior: smooth;
      transition: background-color 0.2s;
    }

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

    img {
      max-width: 100%;
      height: auto;
      display: block;
      border-radius: var(--radius-card);
    }

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

    /* Header & Nav */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--header-height);
      background: white;
      border-bottom: 1px solid var(--border);
      z-index: 1000;
      display: flex;
      align-items: center;
      backdrop-filter: blur(6px);
      background-color: rgba(255,255,255,0.92);
      box-shadow: 0 2px 8px rgba(0,0,0,0.02);
    }

    .nav-container {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
    }

    .logo {
      font-size: 1.55rem;
      font-weight: 700;
      color: var(--primary);
      letter-spacing: -0.3px;
      display: flex;
      align-items: baseline;
      gap: 6px;
    }
    .logo span {
      color: var(--text-secondary);
      font-size: 0.8rem;
      font-weight: 400;
      letter-spacing: 0.2px;
    }

    .nav-menu {
      display: flex;
      gap: 2.2rem;
      align-items: center;
    }

    .nav-link {
      font-weight: 500;
      font-size: 0.98rem;
      color: var(--text);
      position: relative;
      padding: 0.3rem 0;
      transition: color 0.2s;
    }
    .nav-link::after {
      content: '';
      position: absolute;
      bottom: -2px;
      left: 0;
      width: 0%;
      height: 2px;
      background: var(--accent);
      transition: width 0.25s ease;
      border-radius: 2px;
    }
    .nav-link:hover {
      color: var(--accent);
    }
    .nav-link:hover::after {
      width: 100%;
    }

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: transparent;
      border: none;
      padding: 8px;
      z-index: 1100;
    }
    .hamburger span {
      display: block;
      width: 26px;
      height: 3px;
      background: var(--primary);
      border-radius: 3px;
      transition: var(--transition-smooth);
      transform-origin: center;
    }
    .mobile-menu-active .hamburger span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
    .mobile-menu-active .hamburger span:nth-child(2) { opacity: 0; }
    .mobile-menu-active .hamburger span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

    .mobile-nav {
      position: fixed;
      top: 0;
      right: 0;
      width: 75%;
      max-width: 320px;
      height: 100vh;
      background: white;
      box-shadow: -8px 0 30px rgba(0,0,0,0.08);
      transform: translateX(100%);
      transition: transform 0.35s ease;
      display: flex;
      flex-direction: column;
      justify-content: center;
      align-items: center;
      gap: 2rem;
      z-index: 1050;
      padding: 2rem;
    }
    .mobile-nav-active {
      transform: translateX(0);
    }
    .mobile-nav .nav-link {
      font-size: 1.35rem;
      font-weight: 600;
    }

    /* Hero */
    .hero {
      min-height: 85vh;
      display: flex;
      align-items: center;
      background: linear-gradient(135deg, #F8FAFC 0%, #E0F2FE 100%);
      margin-top: var(--header-height);
      padding: 2rem 0;
      position: relative;
      overflow: hidden;
    }
    .hero-content {
      display: flex;
      flex-wrap: wrap;
      align-items: center;
      gap: 3rem;
    }
    .hero-text {
      flex: 1 1 450px;
    }
    .hero-title {
      font-size: 2.9rem;
      font-weight: 700;
      line-height: 1.2;
      letter-spacing: -0.03em;
      color: var(--text);
      margin-bottom: 1.5rem;
    }
    .hero-sub {
      font-size: 1.15rem;
      color: var(--text-secondary);
      max-width: 550px;
      margin-bottom: 2rem;
    }
    .btn {
      display: inline-block;
      font-weight: 600;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      transition: var(--transition-smooth);
      text-align: center;
      cursor: pointer;
      border: 2px solid transparent;
      font-size: 1rem;
    }
    .btn-primary {
      background: var(--cta);
      color: #1E293B;
      border-color: var(--cta);
      box-shadow: 0 6px 14px rgba(245, 158, 11, 0.25);
    }
    .btn-primary:hover {
      background: var(--cta-hover);
      border-color: var(--cta-hover);
      transform: translateY(-2px);
      box-shadow: 0 10px 22px rgba(245, 158, 11, 0.35);
    }
    .btn-outline {
      background: transparent;
      border: 2px solid var(--primary);
      color: var(--primary);
      margin-left: 1rem;
    }
    .btn-outline:hover {
      background: var(--primary);
      color: white;
    }
    .hero-image {
      flex: 1 1 380px;
      background-image: url('/assets/images/backpic/back-1.webp');
      background-size: cover;
      background-position: center;
      border-radius: 32px;
      min-height: 340px;
      box-shadow: var(--shadow-hover);
    }

    /* Sections */
    section {
      padding: 120px 0;
    }
    .section-title {
      font-size: 2rem;
      font-weight: 700;
      margin-bottom: 1rem;
      color: var(--text);
      text-align: center;
    }
    .section-desc {
      color: var(--text-secondary);
      text-align: center;
      max-width: 640px;
      margin: 0 auto 3.5rem;
    }
    .grid-3 {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
      gap: 2rem;
    }
    .card {
      background: var(--card-bg);
      border-radius: var(--radius-card);
      padding: 2rem 1.5rem;
      box-shadow: var(--shadow-sm);
      transition: box-shadow 0.25s, transform 0.25s;
    }
    .card:hover {
      box-shadow: var(--shadow-hover);
      transform: translateY(-4px);
    }

    /* Pain points */
    .pain-card {
      background: #F1F5F9;
      border-left: 4px solid var(--accent);
      padding: 1.8rem;
      border-radius: 8px;
    }

    /* Solution cards */
    .icon-circle {
      background: var(--accent);
      width: 48px;
      height: 48px;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      color: white;
      font-size: 1.6rem;
      margin-bottom: 1.5rem;
    }
    .stats-grid {
      display: flex;
      justify-content: space-around;
      flex-wrap: wrap;
      background: #e6f7f5;
      border-radius: 28px;
      padding: 2.5rem;
      margin-top: 2rem;
    }
    .stat-number {
      font-size: 3rem;
      font-weight: 800;
      color: var(--cta);
    }

    /* Testimonials */
    .testimonial-card {
      background: white;
      padding: 2rem;
      border-radius: 20px;
      display: flex;
      gap: 1.2rem;
      align-items: flex-start;
    }
    .avatar {
      width: 56px;
      height: 56px;
      border-radius: 50%;
      background: #cbd5e1;
      background-image: url('/assets/images/coverpic/cover-3.webp');
      background-size: cover;
    }

    /* FAQ */
    .faq-item {
      border-bottom: 1px solid var(--border);
      padding: 1.5rem 0;
    }
    .faq-question {
      font-weight: 600;
      font-size: 1.1rem;
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease;
      color: var(--text-secondary);
    }
    .faq-answer.open {
      max-height: 180px;
      margin-top: 1rem;
    }

    .cta-banner {
      background: var(--accent);
      border-radius: 28px;
      padding: 4rem 2rem;
      text-align: center;
      color: white;
    }
    .footer {
      background: #0F172A;
      color: #CBD5E1;
      padding: 3rem 0 1.5rem;
    }

    @media (max-width: 768px) {
      .nav-menu { display: none; }
      .hamburger { display: flex; }
      .hero-title { font-size: 2.2rem; }
      section { padding: 80px 0; }
      .container { padding: 0 20px; }
      .hero-content { flex-direction: column; }
      .btn-outline { margin-left: 0; margin-top: 0.8rem; }
    }