/* roulang page: index */
:root {
      --deep-space: #0B0E14;
      --aurora: #00F0C7;
      --nebula: #7B4BFF;
      --text-primary: #FFFFFF;
      --text-secondary: #B0B8C1;
      --text-muted: #6B7280;
      --card-bg: rgba(255,255,255,0.03);
      --card-border: rgba(255,255,255,0.06);
      --radius-lg: 16px;
      --radius-md: 8px;
      --transition-smooth: all 0.3s ease;
    }

    * {
      box-sizing: border-box;
    }

    body {
      margin: 0;
      background-color: var(--deep-space);
      color: var(--text-secondary);
      font-family: 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }

    .font-mono {
      font-family: 'Inter', sans-serif;
    }

    /* 左侧竖向导航 */
    .vertical-nav {
      position: fixed;
      left: 0;
      top: 0;
      width: 72px;
      height: 100vh;
      background-color: var(--deep-space);
      border-right: 1px solid rgba(255,255,255,0.08);
      display: flex;
      flex-direction: column;
      align-items: center;
      padding: 24px 0;
      z-index: 50;
      transition: var(--transition-smooth);
    }

    .nav-logo {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 6px;
      margin-bottom: 40px;
      color: var(--aurora);
      font-weight: 700;
      font-size: 14px;
      letter-spacing: 0.5px;
    }

    .logo-icon {
      width: 28px;
      height: 28px;
      position: relative;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .star-orbit {
      width: 20px;
      height: 20px;
      border: 1.5px solid var(--aurora);
      border-radius: 50%;
      position: relative;
    }

    .star-orbit::after {
      content: '';
      position: absolute;
      top: 2px;
      left: 50%;
      transform: translateX(-50%);
      width: 4px;
      height: 4px;
      background: var(--aurora);
      border-radius: 50%;
      box-shadow: 0 0 8px var(--aurora);
    }

    .nav-items {
      display: flex;
      flex-direction: column;
      gap: 28px;
      flex: 1;
    }

    .nav-item {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 4px;
      color: rgba(255,255,255,0.3);
      text-decoration: none;
      font-size: 10px;
      font-weight: 500;
      transition: var(--transition-smooth);
      position: relative;
      padding: 4px 0;
      width: 100%;
    }

    .nav-item:hover {
      color: var(--aurora);
    }

    .nav-item.active {
      color: var(--aurora);
    }

    .nav-item.active::before {
      content: '';
      position: absolute;
      left: 0;
      top: 0;
      height: 100%;
      width: 2px;
      background: var(--aurora);
      border-radius: 0 2px 2px 0;
    }

    .nav-icon {
      width: 20px;
      height: 20px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 18px;
      transition: transform 0.2s;
    }

    .nav-item:hover .nav-icon {
      transform: scale(1.1);
      filter: drop-shadow(0 0 6px var(--aurora));
    }

    /* 内容区偏移 */
    .main-content {
      margin-left: 72px;
      max-width: 1280px;
      width: calc(100% - 72px);
      margin-right: auto;
      padding: 0 40px;
    }

    @media (max-width: 768px) {
      .vertical-nav {
        display: none;
      }
      .mobile-nav {
        display: flex;
      }
      .main-content {
        margin-left: 0;
        width: 100%;
        padding: 0 20px;
      }
    }

    .mobile-nav {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 56px;
      background: var(--deep-space);
      border-bottom: 1px solid rgba(255,255,255,0.06);
      align-items: center;
      justify-content: space-between;
      padding: 0 20px;
      z-index: 50;
    }

    .mobile-menu {
      position: fixed;
      top: 56px;
      left: 0;
      width: 100%;
      height: calc(100vh - 56px);
      background: var(--deep-space);
      display: flex;
      flex-direction: column;
      padding: 40px 30px;
      gap: 32px;
      transform: translateX(-100%);
      transition: transform 0.25s ease;
      z-index: 49;
    }

    .mobile-menu.open {
      transform: translateX(0);
    }

    .mobile-menu a {
      color: white;
      font-size: 24px;
      font-weight: 500;
      text-decoration: none;
      border-bottom: 1px solid rgba(255,255,255,0.08);
      padding-bottom: 12px;
    }

    /* 卡片通用 */
    .data-card {
      background: var(--card-bg);
      border-radius: var(--radius-lg);
      border: 1px solid var(--card-border);
      transition: var(--transition-smooth);
      backdrop-filter: blur(2px);
    }

    .data-card:hover {
      border-color: var(--aurora);
      box-shadow: var(--glow);
      transform: translateY(-4px);
    }

    .btn-primary {
      background: var(--aurora);
      color: #0B0E14;
      font-weight: 600;
      border-radius: var(--radius-md);
      padding: 12px 28px;
      transition: var(--transition-smooth);
      display: inline-flex;
      align-items: center;
      gap: 8px;
      border: none;
      cursor: pointer;
      font-size: 16px;
    }

    .btn-primary:hover {
      filter: brightness(1.2);
      transform: scale(1.05);
    }

    .btn-secondary {
      background: transparent;
      border: 1px solid var(--aurora);
      color: var(--aurora);
      font-weight: 500;
      border-radius: var(--radius-md);
      padding: 12px 28px;
      transition: var(--transition-smooth);
      cursor: pointer;
      font-size: 16px;
    }

    .btn-secondary:hover {
      background: rgba(0,240,199,0.08);
      color: white;
    }

    .section-title {
      font-size: 32px;
      font-weight: 600;
      line-height: 1.25;
      color: var(--text-primary);
      margin-bottom: 16px;
    }

    @media (max-width: 768px) {
      .section-title {
        font-size: 28px;
      }
    }

    /* 光斑装饰 */
    .aurora-blur {
      position: absolute;
      width: 500px;
      height: 500px;
      background: radial-gradient(circle, rgba(0,240,199,0.15) 0%, transparent 70%);
      filter: blur(120px);
      pointer-events: none;
    }

    /* FAQ 手风琴 */
    .faq-item {
      border-bottom: 1px solid rgba(255,255,255,0.08);
    }

    .faq-question {
      cursor: pointer;
      padding: 20px 0;
      display: flex;
      justify-content: space-between;
      align-items: center;
      color: white;
      font-weight: 500;
      font-size: 18px;
    }

    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.35s ease, padding 0.35s ease;
      color: var(--text-secondary);
      line-height: 1.7;
    }

    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-bottom: 20px;
    }

    .faq-icon {
      font-size: 24px;
      color: var(--aurora);
      transition: transform 0.2s;
    }