/* roulang page: index */
/* ----- 设计变量 & 基础重置 ----- */
    :root {
      --primary: #E63946;
      --primary-hover: #c62831;
      --primary-soft: rgba(230, 57, 70, 0.08);
      --secondary: #264653;
      --secondary-dark: #1b353f;
      --bg-warm: #F8F9FA;
      --white: #FFFFFF;
      --text-dark: #1D1D1D;
      --text-body: #2B2D42;
      --text-muted: #6C757D;
      --border-light: #DEE2E6;
      --shadow-sm: 0 4px 20px rgba(0,0,0,0.06);
      --shadow-hover: 0 12px 30px rgba(0,0,0,0.12);
      --radius-card: 16px;
      --radius-btn: 12px;
      --radius-lg: 20px;
      --font-sans: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --transition: 0.25s ease-in-out;
      --nav-height: 76px;
      --max-width: 1200px;
    }

    * {
      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-warm);
      color: var(--text-body);
      line-height: 1.7;
      -webkit-font-smoothing: antialiased;
      overflow-x: hidden;
    }

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

    a {
      text-decoration: none;
      color: inherit;
    }

    button, .btn {
      cursor: pointer;
      font-family: var(--font-sans);
      border: none;
      outline: none;
      transition: var(--transition);
    }

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

    /* ----- 导航 (沉浸式动态导航) ----- */
    .navbar {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--nav-height);
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 0 32px;
      z-index: 1000;
      transition: background 0.3s ease, box-shadow 0.3s ease;
      background: transparent;
    }

    .navbar.scrolled {
      background: var(--secondary);
      box-shadow: 0 8px 20px rgba(0,0,0,0.18);
    }

    .logo {
      font-size: 1.9rem;
      font-weight: 700;
      letter-spacing: 1px;
      color: white;
      display: flex;
      align-items: center;
      gap: 5px;
    }
    .logo i {
      color: var(--primary);
      font-size: 2.2rem;
    }

    .nav-links {
      display: flex;
      align-items: center;
      gap: 2.5rem;
      font-weight: 500;
      color: rgba(255,255,255,0.9);
    }

    .nav-links a {
      position: relative;
      padding: 6px 0;
      transition: color 0.2s;
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--primary);
      transition: width 0.25s;
    }
    .nav-links a:hover {
      color: white;
    }
    .nav-links a:hover::after {
      width: 100%;
    }

    .nav-cta {
      background: var(--primary);
      color: white;
      padding: 12px 26px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      margin-left: 1.5rem;
      box-shadow: 0 4px 12px rgba(230,57,70,0.4);
    }
    .nav-cta:hover {
      background: var(--primary-hover);
      box-shadow: 0 8px 18px rgba(230,57,70,0.5);
    }

    .hamburger {
      display: none;
      font-size: 1.8rem;
      color: white;
      cursor: pointer;
    }

    .mobile-menu {
      display: none;
    }

    /* ----- 英雄首屏 Hero ----- */
    .hero {
      height: 100vh;
      min-height: 650px;
      display: flex;
      align-items: center;
      background: linear-gradient(135deg, rgba(38,70,83,0.82) 0%, rgba(0,0,0,0.5) 100%), url('/assets/images/backpic/back-1.webp') center/cover no-repeat;
      background-blend-mode: overlay;
      position: relative;
      padding-top: var(--nav-height);
    }

    .hero-content {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 2.5rem;
      width: 100%;
    }

    .hero-text {
      flex: 1 1 50%;
      color: white;
      max-width: 600px;
    }
    .hero-text h1 {
      font-size: 3.6rem;
      font-weight: 700;
      line-height: 1.2;
      margin-bottom: 1.5rem;
      color: white;
      text-shadow: 0 4px 12px rgba(0,0,0,0.3);
    }
    .hero-text h2 {
      font-size: 1.6rem;
      font-weight: 400;
      opacity: 0.9;
      margin-bottom: 2rem;
      color: rgba(255,255,255,0.9);
    }
    .hero-buttons {
      display: flex;
      gap: 1.2rem;
      flex-wrap: wrap;
    }
    .btn-primary {
      background: var(--primary);
      color: white;
      padding: 16px 36px;
      border-radius: var(--radius-btn);
      font-weight: 700;
      font-size: 1.1rem;
      box-shadow: 0 10px 20px rgba(230,57,70,0.4);
    }
    .btn-primary:hover {
      background: var(--primary-hover);
      transform: translateY(-2px);
    }
    .btn-outline {
      background: transparent;
      border: 2px solid white;
      color: white;
      padding: 16px 36px;
      border-radius: var(--radius-btn);
      font-weight: 600;
    }
    .btn-outline:hover {
      background: white;
      color: var(--secondary);
    }

    .hero-visual {
      flex: 1 1 45%;
      display: flex;
      justify-content: center;
    }
    .hero-visual img {
      border-radius: var(--radius-lg);
      box-shadow: 0 20px 40px rgba(0,0,0,0.5);
      max-height: 480px;
      object-fit: cover;
    }

    /* ----- 核心优势 (不对称网格) ----- */
    .section {
      padding: 90px 0;
    }
    .section-title {
      text-align: center;
      margin-bottom: 60px;
    }
    .section-title h2 {
      font-size: 2.5rem;
      font-weight: 700;
      color: var(--text-dark);
      position: relative;
      display: inline-block;
    }
    .section-title h2::after {
      content: '';
      position: absolute;
      bottom: -12px;
      left: 50%;
      transform: translateX(-50%);
      width: 60px;
      height: 4px;
      background: var(--primary);
      border-radius: 2px;
    }

    .features-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 28px;
    }
    .feature-card {
      background: var(--white);
      border-radius: var(--radius-card);
      padding: 32px;
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
      display: flex;
      flex-direction: column;
      border-left: 5px solid transparent;
    }
    .feature-card:first-child {
      grid-row: span 2;
      border-left-color: var(--primary);
    }
    .feature-card:nth-child(2), .feature-card:nth-child(3) {
      border-left-color: var(--secondary);
    }
    .feature-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-hover);
    }
    .feature-icon {
      font-size: 2.7rem;
      color: var(--primary);
      margin-bottom: 20px;
    }
    .feature-card h3 {
      font-size: 1.6rem;
      font-weight: 700;
      margin-bottom: 14px;
      color: var(--text-dark);
    }

    /* ----- 使用场景 ----- */
    .scenarios-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 28px;
    }
    .scenario-card {
      background: var(--white);
      border-radius: var(--radius-card);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
    }
    .scenario-card:hover {
      transform: translateY(-8px);
      box-shadow: var(--shadow-hover);
    }
    .scenario-img {
      height: 220px;
      overflow: hidden;
    }
    .scenario-img img {
      width: 100%;
      height: 100%;
      object-fit: cover;
      transition: transform 0.4s;
    }
    .scenario-card:hover .scenario-img img {
      transform: scale(1.05);
    }
    .scenario-info {
      padding: 22px;
    }

    /* ----- 数据案例 ----- */
    .case-row {
      display: flex;
      gap: 40px;
      align-items: center;
    }
    .stats-block {
      display: grid;
      grid-template-columns: repeat(2,1fr);
      gap: 32px;
      flex:1;
    }
    .stat-item {
      background: var(--white);
      padding: 24px;
      border-radius: var(--radius-card);
      text-align: center;
      box-shadow: var(--shadow-sm);
    }
    .stat-number {
      font-size: 2.8rem;
      font-weight: 800;
      color: var(--primary);
    }

    /* ----- FAQ 手风琴 ----- */
    .faq-item {
      background: var(--white);
      border-radius: 12px;
      margin-bottom: 16px;
      box-shadow: var(--shadow-sm);
    }
    .faq-question {
      padding: 20px 28px;
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      cursor: pointer;
      color: var(--text-dark);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: 0.3s;
      padding: 0 28px;
      background: var(--primary-soft);
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding: 20px 28px;
    }

    /* ----- 页脚 CTA ----- */
    .footer-cta {
      background: var(--secondary);
      color: white;
      padding: 60px 0;
      text-align: center;
    }
    .footer-bottom {
      background: #1b353f;
      color: #aaa;
      padding: 24px;
    }

    @media (max-width: 1024px) {
      .hero-content { flex-direction: column; text-align: center; }
      .hero-text h1 { font-size: 2.8rem; }
      .features-grid { grid-template-columns: 1fr; }
    }
    @media (max-width: 768px) {
      .nav-links { display: none; }
      .hamburger { display: block; }
      .scenarios-grid { grid-template-columns: 1fr; }
    }