/* roulang page: index */
/* ===== 设计变量 ===== */
    :root {
      --primary: #D32F2F;      /* 竞技红 */
      --primary-dark: #B71C1C;
      --secondary: #1B1B1B;    /* 深岩黑 */
      --accent: #FFC107;       /* 琥珀金 */
      --accent-hover: #E5A800;
      --bg-light: #FAFAFA;
      --bg-dark: #1B1B1B;
      --text-dark: #1B1B1B;
      --text-gray: #444444;
      --text-light: #CCCCCC;
      --white: #FFFFFF;
      --card-bg: #FFFFFF;
      --card-dark-bg: #2A2A2A;
      --border-light: #E0E0E0;
      --shadow-sm: 0 8px 30px rgba(0,0,0,0.06);
      --shadow-hover: 0 16px 40px rgba(0,0,0,0.12);
      --radius-sm: 8px;
      --radius-md: 12px;
      --radius-lg: 20px;
      --font-sans: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
      --transition: 0.25s ease;
      --container-max: 1200px;
      --nav-height: 80px;
      --nav-height-mobile: 64px;
    }

    /* ===== Reset & Base ===== */
    *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
    html { scroll-behavior: smooth; }
    body {
      font-family: var(--font-sans);
      font-size: 16px;
      line-height: 1.7;
      font-weight: 400;
      color: var(--text-dark);
      background-color: var(--white);
      -webkit-font-smoothing: antialiased;
      overflow-x: hidden;
    }
    img { max-width: 100%; height: auto; display: block; }
    a { text-decoration: none; color: inherit; transition: var(--transition); }
    button, input { font-family: inherit; }
    .container {
      width: 100%;
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 24px;
    }

    /* ===== 导航 ===== */
    #header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--nav-height);
      display: flex;
      align-items: center;
      justify-content: center;
      z-index: 1000;
      transition: background var(--transition), box-shadow var(--transition), backdrop-filter var(--transition);
      background: transparent;
    }
    #header.scrolled {
      background: rgba(255,255,255,0.92);
      backdrop-filter: blur(12px);
      box-shadow: 0 4px 20px rgba(0,0,0,0.08);
    }
    .nav-container {
      width: 100%;
      max-width: var(--container-max);
      padding: 0 24px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 100%;
    }
    .logo {
      display: flex;
      align-items: center;
      gap: 8px;
      font-size: 1.6rem;
      font-weight: 800;
      letter-spacing: 0.5px;
      color: var(--white);
      transition: color var(--transition);
    }
    #header.scrolled .logo { color: var(--text-dark); }
    .logo-icon {
      width: 36px;
      height: 36px;
      background: linear-gradient(135deg, var(--accent), var(--primary));
      border-radius: 8px;
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--white);
      font-size: 1.2rem;
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 2rem;
      list-style: none;
    }
    .nav-links a {
      color: rgba(255,255,255,0.9);
      font-weight: 500;
      font-size: 0.95rem;
      position: relative;
      padding: 0.25rem 0;
    }
    #header.scrolled .nav-links a { color: var(--text-dark); }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: -2px;
      left: 0;
      width: 0%;
      height: 2px;
      background: var(--accent);
      transition: width var(--transition);
    }
    .nav-links a:hover::after { width: 100%; }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      background: none;
      border: none;
      cursor: pointer;
      padding: 8px;
    }
    .hamburger span {
      display: block;
      width: 26px;
      height: 2px;
      background: var(--white);
      transition: var(--transition);
    }
    #header.scrolled .hamburger span { background: var(--text-dark); }

    /* ===== Hero 首屏 ===== */
    #hero {
      height: 100vh;
      min-height: 700px;
      background: url('/assets/images/backpic/back-1.webp') center/cover no-repeat;
      position: relative;
      display: flex;
      align-items: center;
      justify-content: center;
      text-align: center;
    }
    #hero::before {
      content: '';
      position: absolute;
      inset: 0;
      background: linear-gradient(180deg, rgba(27,27,27,0.75) 0%, rgba(27,27,27,0.5) 100%);
      z-index: 1;
    }
    .hero-content {
      position: relative;
      z-index: 2;
      max-width: 800px;
      color: var(--white);
    }
    .hero-content h1 {
      font-size: clamp(2.5rem, 6vw, 4rem);
      font-weight: 800;
      letter-spacing: -0.5px;
      line-height: 1.15;
      text-shadow: 0 4px 20px rgba(0,0,0,0.5);
    }
    .hero-content .subtitle {
      font-size: 1.15rem;
      color: rgba(255,255,255,0.8);
      margin: 1.25rem 0 2rem;
    }
    .btn-group { display: flex; gap: 1.25rem; justify-content: center; flex-wrap: wrap; }
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 14px 36px;
      border-radius: var(--radius-sm);
      font-weight: 700;
      font-size: 1rem;
      transition: var(--transition);
      border: 2px solid transparent;
      cursor: pointer;
    }
    .btn-primary {
      background: var(--accent);
      color: var(--secondary);
      border-color: var(--accent);
    }
    .btn-primary:hover {
      background: var(--accent-hover);
      border-color: var(--accent-hover);
      transform: scale(1.03);
    }
    .btn-outline {
      background: transparent;
      color: var(--white);
      border-color: var(--white);
    }
    .btn-outline:hover {
      background: var(--white);
      color: var(--secondary);
      transform: scale(1.03);
    }
    .floating-geo {
      position: absolute;
      z-index: 1;
      opacity: 0.25;
      pointer-events: none;
    }
    .geo-circle {
      width: 120px;
      height: 120px;
      border: 3px solid var(--accent);
      border-radius: 50%;
      top: 15%;
      left: 10%;
      animation: float 8s infinite alternate;
    }
    .geo-triangle {
      width: 0;
      height: 0;
      border-left: 50px solid transparent;
      border-right: 50px solid transparent;
      border-bottom: 90px solid var(--accent);
      bottom: 12%;
      right: 8%;
      animation: float 10s infinite alternate-reverse;
    }
    @keyframes float {
      0% { transform: translateY(0px); }
      100% { transform: translateY(-25px); }
    }

    /* ===== 通用区块 ===== */
    section { padding: 100px 0; }
    .section-title {
      font-size: 2.2rem;
      font-weight: 700;
      text-align: center;
      margin-bottom: 3rem;
      position: relative;
    }
    .section-title::after {
      content: '';
      display: block;
      width: 60px;
      height: 3px;
      background: var(--accent);
      margin: 0.75rem auto 0;
    }
    .bg-light { background: var(--bg-light); }
    .bg-dark { background: var(--bg-dark); color: var(--white); }

    /* ===== 核心优势 ===== */
    .features-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 30px;
    }
    .feature-card {
      background: var(--card-bg);
      border-radius: var(--radius-md);
      padding: 32px 24px;
      text-align: center;
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
    }
    .feature-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-hover);
    }
    .feature-icon {
      width: 64px;
      height: 64px;
      background: var(--bg-light);
      border-radius: 18px;
      display: flex;
      align-items: center;
      justify-content: center;
      margin: 0 auto 1.25rem;
      font-size: 2rem;
      color: var(--primary);
      transition: var(--transition);
    }
    .feature-card:hover .feature-icon {
      background: var(--primary);
      color: var(--white);
    }
    .feature-card h3 { font-size: 1.25rem; font-weight: 600; margin-bottom: 0.5rem; }

    /* ===== 数据统计 ===== */
    .stats-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 30px;
      text-align: center;
    }
    .stat-number {
      font-size: 3rem;
      font-weight: 800;
      color: var(--accent);
      margin-bottom: 0.25rem;
    }

    /* ===== 服务卡片 ===== */
    .services-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 30px;
    }
    .service-card {
      border-radius: var(--radius-md);
      overflow: hidden;
      background: var(--card-bg);
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
    }
    .service-card:hover {
      transform: translateY(-5px);
      box-shadow: var(--shadow-hover);
    }
    .service-img {
      height: 200px;
      background-size: cover;
      background-position: center;
      position: relative;
    }
    .service-img::after {
      content: '';
      position: absolute;
      inset: 0;
      background: linear-gradient(0deg, rgba(211,47,47,0.7) 0%, transparent 60%);
    }
    .service-body {
      padding: 24px;
    }
    .service-body h3 { font-size: 1.25rem; margin-bottom: 0.5rem; }
    .text-link {
      color: var(--primary);
      font-weight: 600;
      display: inline-flex;
      align-items: center;
      gap: 4px;
      margin-top: 0.75rem;
    }

    /* ===== 时间线 ===== */
    .timeline {
      position: relative;
      max-width: 800px;
      margin: 0 auto;
    }
    .timeline::before {
      content: '';
      position: absolute;
      left: 50%;
      transform: translateX(-50%);
      width: 3px;
      height: 100%;
      background: var(--primary);
      opacity: 0.3;
    }
    .timeline-item {
      display: flex;
      align-items: flex-start;
      margin-bottom: 2.5rem;
      position: relative;
    }
    .timeline-item:nth-child(odd) { flex-direction: row; }
    .timeline-item:nth-child(even) { flex-direction: row-reverse; }
    .timeline-dot {
      width: 16px;
      height: 16px;
      background: var(--primary);
      border-radius: 50%;
      position: absolute;
      left: 50%;
      transform: translateX(-50%);
      z-index: 2;
    }
    .timeline-content {
      width: 45%;
      background: var(--card-bg);
      padding: 20px;
      border-radius: var(--radius-md);
      box-shadow: var(--shadow-sm);
    }

    /* ===== FAQ 手风琴 ===== */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 1rem 0;
    }
    .faq-question {
      width: 100%;
      background: none;
      border: none;
      font-size: 1.1rem;
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
      padding: 0.75rem 0;
      color: var(--text-dark);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      color: var(--text-gray);
    }
    .faq-item.active .faq-answer { max-height: 200px; padding-bottom: 0.75rem; }
    .faq-item.active .faq-question { color: var(--primary); }

    /* ===== CTA 横幅 ===== */
    #cta {
      background: url('/assets/images/backpic/back-2.webp') center/cover no-repeat;
      position: relative;
    }
    #cta::before {
      content: '';
      position: absolute;
      inset: 0;
      background: rgba(27,27,27,0.8);
    }
    #cta .container { position: relative; z-index: 2; }

    /* ===== 页脚 ===== */
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
    }
    .social-icons { display: flex; gap: 1rem; font-size: 1.5rem; }

    /* ===== 响应式 ===== */
    @media (max-width: 992px) {
      .features-grid { grid-template-columns: repeat(2, 1fr); }
      .services-grid { grid-template-columns: repeat(2, 1fr); }
      .stats-grid { grid-template-columns: repeat(2, 1fr); }
    }
    @media (max-width: 768px) {
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .features-grid, .services-grid, .stats-grid { grid-template-columns: 1fr; }
      .footer-grid { grid-template-columns: 1fr; }
      .timeline::before { left: 20px; }
      .timeline-item, .timeline-item:nth-child(even) { flex-direction: row; }
      .timeline-dot { left: 20px; }
      .timeline-content { width: calc(100% - 50px); margin-left: 40px; }
    }