/* roulang page: index */
/* ----- 设计变量与基础重置 ----- */
    :root {
      --deep-space: #0A0E27;
      --energy-orange: #FF4D00;
      --electric-cyan: #00E5FF;
      --titanium: #B0B8C1;
      --card-bg: rgba(15, 25, 45, 0.65);
      --card-border: rgba(255, 255, 255, 0.08);
      --glass-shadow: 0 8px 32px rgba(0, 0, 0, 0.5);
      --transition-smooth: all 0.3s cubic-bezier(0.2, 0.9, 0.4, 1);
      --font-stack: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
      --container-max: 1200px;
      --nav-height: 80px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    html {
      scroll-behavior: smooth;
      background-color: var(--deep-space);
    }
    body {
      font-family: var(--font-stack);
      background: radial-gradient(circle at 20% 10%, #141a35 0%, #0A0E27 70%);
      color: var(--titanium);
      line-height: 1.7;
      font-weight: 400;
      overflow-x: hidden;
      position: relative;
    }
    /* 网格背景纹理 */
    body::before {
      content: "";
      position: fixed;
      top: 0;
      left: 0;
      right: 0;
      bottom: 0;
      background-image: 
        linear-gradient(rgba(0, 229, 255, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(0, 229, 255, 0.03) 1px, transparent 1px);
      background-size: 40px 40px;
      pointer-events: none;
      z-index: 0;
    }
    .container {
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 24px;
      position: relative;
      z-index: 1;
    }
    h1, h2, h3 {
      font-weight: 700;
      letter-spacing: -0.02em;
      color: white;
      line-height: 1.3;
    }
    h1 { font-size: 2.8rem; }
    h2 { font-size: 2.2rem; margin-bottom: 0.5rem; }
    h3 { font-size: 1.5rem; }
    p { margin-bottom: 1rem; }
    a, button {
      text-decoration: none;
      transition: var(--transition-smooth);
    }
    img {
      max-width: 100%;
      display: block;
    }
    /* ----- 导航 (胶囊玻璃态) ----- */
    .site-header {
      position: fixed;
      top: 20px;
      left: 50%;
      transform: translateX(-50%);
      width: calc(100% - 40px);
      max-width: 1100px;
      height: var(--nav-height);
      background: rgba(10, 14, 39, 0.8);
      backdrop-filter: blur(20px);
      -webkit-backdrop-filter: blur(20px);
      border: 1px solid rgba(255, 255, 255, 0.08);
      border-radius: 60px;
      box-shadow: 0 20px 40px rgba(0,0,0,0.6);
      z-index: 999;
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 0 32px;
      transition: var(--transition-smooth);
    }
    .logo {
      font-size: 1.7rem;
      font-weight: 700;
      color: white;
      letter-spacing: -0.5px;
    }
    .logo span {
      color: var(--energy-orange);
    }
    .nav-links {
      display: flex;
      gap: 2.5rem;
    }
    .nav-links a {
      color: var(--titanium);
      font-weight: 500;
      font-size: 1rem;
      position: relative;
      padding: 6px 0;
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--electric-cyan);
      transition: width 0.3s ease;
      box-shadow: 0 0 8px var(--electric-cyan);
    }
    .nav-links a:hover {
      color: var(--electric-cyan);
    }
    .nav-links a:hover::after { width: 100%; }
    .hamburger {
      display: none;
      flex-direction: column;
      cursor: pointer;
    }
    .hamburger div {
      width: 28px;
      height: 3px;
      background: var(--energy-orange);
      margin: 4px 0;
      border-radius: 3px;
      transition: 0.3s;
    }
    /* hero canvas 粒子 */
    #particle-canvas {
      position: absolute;
      top:0;
      left:0;
      width:100%;
      height:100%;
      z-index:0;
    }
    /* ----- 按钮 ----- */
    .btn-primary {
      background: var(--energy-orange);
      border: none;
      color: white;
      padding: 14px 36px;
      border-radius: 50px;
      font-weight: 700;
      font-size: 1rem;
      box-shadow: 0 0 25px rgba(255, 77, 0, 0.7);
      display: inline-block;
      text-align: center;
      cursor: pointer;
    }
    .btn-primary:hover {
      background: #ff6a1f;
      box-shadow: 0 0 40px rgba(255, 77, 0, 0.9);
      transform: translateY(-3px);
    }
    .btn-secondary {
      background: transparent;
      border: 1px solid var(--electric-cyan);
      color: var(--electric-cyan);
      padding: 14px 36px;
      border-radius: 50px;
      font-weight: 600;
      display: inline-block;
    }
    .btn-secondary:hover {
      background: rgba(0, 229, 255, 0.08);
      border-color: white;
      color: white;
    }
    /* 玻璃卡片 */
    .glass-card {
      background: var(--card-bg);
      backdrop-filter: blur(14px);
      -webkit-backdrop-filter: blur(14px);
      border: 1px solid var(--card-border);
      border-radius: 24px;
      padding: 2rem;
      box-shadow: var(--glass-shadow);
      transition: all 0.4s ease;
    }
    .glass-card:hover {
      border-color: var(--electric-cyan);
      box-shadow: 0 12px 40px rgba(0, 229, 255, 0.25);
    }
    /* FAQ */
    .faq-item {
      border-bottom: 1px solid rgba(255,255,255,0.08);
      overflow: hidden;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      align-items: center;
      padding: 1.8rem 0;
      font-weight: 600;
      font-size: 1.2rem;
      color: white;
      cursor: pointer;
      user-select: none;
    }
    .faq-question i { color: var(--electric-cyan); transition: 0.3s; }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.5s cubic-bezier(0.4, 0, 0.2, 1);
      background: rgba(255,255,255,0.02);
    }
    .faq-answer.active { max-height: 300px; }
    .faq-content {
      padding: 0 0 2rem 0;
      position: relative;
      border-left: 3px solid var(--energy-orange);
      margin-left: 10px;
      padding-left: 1.5rem;
    }
    /* 响应式 */
    @media (max-width: 1024px) {
      h1 { font-size: 2.4rem; } h2 { font-size: 1.9rem; }
      .site-header { width: 95%; }
    }
    @media (max-width: 768px) {
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .mobile-menu {
        display: none;
        position: absolute;
        top: 80px;
        left: 0;
        width: 100%;
        background: rgba(8, 12, 30, 0.95);
        backdrop-filter: blur(25px);
        border-radius: 32px;
        flex-direction: column;
        align-items: center;
        padding: 2rem;
        gap: 2rem;
      }
      .mobile-menu.open { display: flex; }
      h1 { font-size: 2rem; } h2 { font-size: 1.8rem; }
      .container { padding: 0 20px; }
    }