/* roulang page: index */
/* 自定义 CSS 变量与全局样式 */
    :root {
      --brand-orange: #FF4C00;
      --brand-orange-dark: #E04300;
      --deep-charcoal: #1E1E1E;
      --void-black: #0F0F0F;
      --titanium-gray: #E0E0E0;
      --soft-gray: #CCCCCC;
      --card-border: rgba(255,255,255,0.08);
      --font-display: 'Bebas Neue', 'Impact', '思源黑体 Heavy', 'Source Han Sans Heavy', system-ui, sans-serif;
      --font-body: 'Inter', 'Roboto', 'PingFang SC', 'Microsoft YaHei', '苹方', system-ui, sans-serif;
      --radius-xl: 12px;
      --radius-btn: 6px;
      --shadow-glow: 0 0 20px rgba(255,76,0,0.3);
    }
    
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    
    html {
      scroll-behavior: smooth;
      background-color: var(--deep-charcoal);
    }
    
    body {
      font-family: var(--font-body);
      background-color: var(--deep-charcoal);
      color: var(--titanium-gray);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }
    
    /* 容器 */
    .container-custom {
      max-width: 1280px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 20px;
      padding-right: 20px;
    }
    
    /* 导航基础 */
    .nav-blur {
      background: rgba(15, 15, 15, 0.85);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
    }
    
    .nav-link {
      color: #CCCCCC;
      transition: color 0.3s ease, border-bottom 0.2s ease;
      border-bottom: 2px solid transparent;
      padding-bottom: 4px;
      font-weight: 500;
    }
    .nav-link:hover {
      color: var(--brand-orange);
      border-bottom-color: var(--brand-orange);
    }
    
    /* 按钮样式 */
    .btn-primary {
      background-color: var(--brand-orange);
      color: white;
      font-weight: 700;
      border-radius: var(--radius-btn);
      padding: 14px 32px;
      letter-spacing: 0.5px;
      transition: background-color 0.3s ease, box-shadow 0.3s ease, transform 0.2s ease;
      display: inline-block;
      text-align: center;
      border: none;
      cursor: pointer;
      box-shadow: 0 4px 12px rgba(255,76,0,0.25);
    }
    .btn-primary:hover {
      background-color: var(--brand-orange-dark);
      box-shadow: 0 0 25px rgba(255,76,0,0.5);
      transform: translateY(-2px);
    }
    
    .btn-outline {
      background: transparent;
      border: 2px solid var(--brand-orange);
      color: var(--brand-orange);
      font-weight: 700;
      border-radius: var(--radius-btn);
      padding: 12px 32px;
      letter-spacing: 0.5px;
      transition: all 0.3s ease;
      display: inline-block;
      text-align: center;
      cursor: pointer;
    }
    .btn-outline:hover {
      background-color: var(--brand-orange);
      color: white;
      box-shadow: 0 0 20px rgba(255,76,0,0.4);
    }
    
    /* 卡片样式 */
    .feature-card {
      background-color: var(--void-black);
      border: 1px solid var(--card-border);
      border-radius: var(--radius-xl);
      padding: 32px 24px;
      transition: transform 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
    }
    .feature-card:hover {
      border-color: var(--brand-orange);
      box-shadow: var(--shadow-glow);
      transform: translateY(-4px);
    }
    .feature-icon {
      color: var(--brand-orange);
      transition: transform 0.3s ease;
    }
    .feature-card:hover .feature-icon {
      transform: scale(1.15) rotate(5deg);
    }
    
    /* 手风琴样式 */
    .faq-item {
      border-bottom: 1px solid rgba(255,255,255,0.1);
      padding: 20px 0;
      cursor: pointer;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-weight: 600;
      color: white;
      font-size: 1.1rem;
    }
    .faq-icon {
      transition: transform 0.3s ease;
      color: var(--brand-orange);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease, padding 0.3s ease;
      color: #AAAAAA;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-top: 12px;
    }
    .faq-item.active .faq-icon {
      transform: rotate(45deg);
    }
    
    /* 数字动画相关 */
    .counter-number {
      font-family: var(--font-display);
      font-weight: 900;
      color: var(--brand-orange);
    }
    
    /* 移动端底部导航 */
    .mobile-nav {
      background-color: var(--void-black);
      border-top: 1px solid rgba(255,255,255,0.1);
    }
    
    /* 速度线背景动画 (装饰) */
    .speed-line-bg {
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      overflow: hidden;
      z-index: 0;
    }
    .speed-line {
      position: absolute;
      width: 2px;
      height: 40px;
      background: linear-gradient(to bottom, rgba(255,76,0,0.4), transparent);
      animation: moveDown 3s linear infinite;
    }
    @keyframes moveDown {
      0% { transform: translateY(-100px); opacity: 0; }
      50% { opacity: 0.6; }
      100% { transform: translateY(100vh); opacity: 0; }
    }
    
    /* 响应式调整 */
    @media (max-width: 768px) {
      .container-custom {
        padding-left: 16px;
        padding-right: 16px;
      }
      .btn-primary, .btn-outline {
        padding: 12px 24px;
        font-size: 0.95rem;
      }
      h1 {
        font-size: 2.5rem !important;
      }
      h2 {
        font-size: 2rem !important;
      }
      .feature-card {
        padding: 24px 20px;
      }
      .counter-number {
        font-size: 2.5rem !important;
      }
    }