/* roulang page: index */
:root {
      --primary-deep: #0A0E27;
      --glass-bg: rgba(27, 42, 74, 0.5);
      --glass-border: rgba(0, 212, 255, 0.25);
      --accent-cyan: #00D4FF;
      --accent-purple: #7B61FF;
      --success-green: #00E5A0;
      --text-white: #FFFFFF;
      --text-light-steel: #B0C4DE;
      --text-muted: #6B7B94;
      --border-dim: #2E3B5C;
      --card-radius: 16px;
      --btn-radius: 8px;
      --shadow-glass: 0 10px 30px rgba(0,0,0,0.5);
      --glow-cyan: 0 0 18px rgba(0,212,255,0.4);
      --transition-smooth: all 0.25s ease;
      --container-max: 1200px;
      --nav-width: 72px;
      --nav-expand: 240px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    body {
      font-family: 'Inter', 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
      background-color: var(--primary-deep);
      color: var(--text-light-steel);
      line-height: 1.7;
      font-weight: 400;
      -webkit-font-smoothing: antialiased;
      overflow-x: hidden;
      background-image: radial-gradient(circle at 30% 20%, rgba(123, 97, 255, 0.08) 0%, transparent 40%),
                        radial-gradient(circle at 80% 70%, rgba(0,212,255,0.05) 0%, transparent 45%);
      background-attachment: fixed;
    }
    .container {
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 24px;
    }
    h1, h2, h3, h4 {
      color: var(--text-white);
      font-weight: 700;
      letter-spacing: -0.02em;
    }
    h1 { font-size: 3rem; line-height: 1.2; }
    h2 { font-size: 2.25rem; }
    h3 { font-size: 1.5rem; }
    a {
      color: var(--accent-cyan);
      text-decoration: none;
      transition: var(--transition-smooth);
    }
    a:hover { color: #66e3ff; }
    img {
      max-width: 100%;
      display: block;
      border-radius: 12px;
    }
    button, .btn {
      cursor: pointer;
      font-family: inherit;
      font-weight: 600;
      border: none;
      transition: var(--transition-smooth);
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
    }
    /* 左侧竖向导航 */
    .side-nav {
      position: fixed;
      left: 0;
      top: 0;
      height: 100vh;
      width: var(--nav-width);
      background: rgba(10, 14, 39, 0.85);
      backdrop-filter: blur(24px) saturate(160%);
      -webkit-backdrop-filter: blur(24px) saturate(160%);
      border-right: 1px solid rgba(0, 212, 255, 0.15);
      display: flex;
      flex-direction: column;
      align-items: center;
      padding: 24px 0;
      z-index: 1000;
      transition: width 0.3s cubic-bezier(0.2, 0.9, 0.4, 1);
      overflow: hidden;
    }
    .side-nav:hover {
      width: var(--nav-expand);
    }
    .nav-logo {
      display: flex;
      align-items: center;
      gap: 12px;
      margin-bottom: 48px;
      padding: 0 16px;
      white-space: nowrap;
      width: 100%;
      justify-content: center;
    }
    .nav-logo i {
      font-size: 28px;
      color: var(--accent-cyan);
      filter: drop-shadow(0 0 8px rgba(0,212,255,0.7));
    }
    .nav-logo span {
      font-weight: 700;
      font-size: 1.2rem;
      color: white;
      display: none;
      letter-spacing: 1px;
    }
    .side-nav:hover .nav-logo span {
      display: inline;
    }
    .nav-menu {
      list-style: none;
      width: 100%;
      display: flex;
      flex-direction: column;
      gap: 8px;
      padding: 0 12px;
    }
    .nav-item {
      display: flex;
      align-items: center;
      gap: 16px;
      padding: 14px 12px;
      border-radius: 8px;
      color: var(--text-muted);
      transition: var(--transition-smooth);
      white-space: nowrap;
      position: relative;
      text-decoration: none;
      font-weight: 500;
    }
    .nav-item i {
      font-size: 22px;
      width: 24px;
      text-align: center;
      color: var(--text-muted);
      transition: var(--transition-smooth);
    }
    .nav-item span {
      display: none;
      opacity: 0;
      transition: opacity 0.2s;
    }
    .side-nav:hover .nav-item span {
      display: inline;
      opacity: 1;
    }
    .nav-item:hover, .nav-item.active {
      background: rgba(0, 212, 255, 0.1);
      color: white;
    }
    .nav-item.active::before {
      content: '';
      position: absolute;
      left: 0;
      top: 8px;
      bottom: 8px;
      width: 3px;
      background: var(--accent-cyan);
      border-radius: 0 4px 4px 0;
      box-shadow: 0 0 12px var(--accent-cyan);
    }
    .nav-item:hover i, .nav-item.active i {
      color: var(--accent-cyan);
    }
    .nav-bottom {
      margin-top: auto;
      padding: 20px 12px;
      color: var(--text-muted);
      font-size: 20px;
    }
    /* 移动端顶部导航 */
    .mobile-header {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      right: 0;
      height: 56px;
      background: rgba(10, 14, 39, 0.9);
      backdrop-filter: blur(20px);
      -webkit-backdrop-filter: blur(20px);
      z-index: 999;
      align-items: center;
      justify-content: space-between;
      padding: 0 20px;
      border-bottom: 1px solid rgba(0,212,255,0.2);
    }
    .mobile-logo {
      display: flex;
      align-items: center;
      gap: 8px;
      font-weight: 700;
      color: white;
    }
    .hamburger {
      font-size: 24px;
      color: white;
      background: transparent;
      border: none;
    }
    .mobile-menu-panel {
      position: fixed;
      top: 56px;
      left: 0;
      right: 0;
      bottom: 0;
      background: rgba(10, 14, 39, 0.96);
      backdrop-filter: blur(28px);
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 32px;
      z-index: 998;
      transform: translateX(100%);
      transition: transform 0.3s ease;
    }
    .mobile-menu-panel.open {
      transform: translateX(0);
    }
    .mobile-menu-panel a {
      font-size: 1.8rem;
      color: var(--text-light-steel);
      font-weight: 600;
    }
    /* 主内容区偏移 */
    .main-content {
      margin-left: var(--nav-width);
      transition: margin-left 0.3s;
    }
    /* 通用板块 */
    section {
      padding: 90px 0;
      position: relative;
    }
    .section-title {
      text-align: center;
      margin-bottom: 48px;
    }
    .glass-card {
      background: rgba(27, 42, 74, 0.45);
      backdrop-filter: blur(20px) saturate(140%);
      -webkit-backdrop-filter: blur(20px) saturate(140%);
      border: 1px solid rgba(0, 212, 255, 0.18);
      border-radius: var(--card-radius);
      box-shadow: 0 8px 28px rgba(0,0,0,0.45);
      transition: all 0.3s ease;
    }
    .glass-card:hover {
      border-color: rgba(0, 212, 255, 0.45);
      box-shadow: 0 12px 36px rgba(0,212,255,0.2);
      transform: translateY(-4px);
    }
    .btn-primary {
      background: var(--accent-cyan);
      color: #0A0E27;
      padding: 14px 32px;
      border-radius: var(--btn-radius);
      font-weight: 700;
      box-shadow: 0 4px 18px rgba(0,212,255,0.4);
    }
    .btn-primary:hover {
      background: #33DDFF;
      box-shadow: 0 0 24px rgba(0,212,255,0.7);
      transform: scale(1.02);
    }
    .btn-outline {
      background: transparent;
      border: 1px solid var(--accent-cyan);
      color: var(--accent-cyan);
      padding: 14px 32px;
      border-radius: var(--btn-radius);
    }
    .btn-outline:hover {
      background: rgba(0,212,255,0.1);
    }
    @media (max-width: 1024px) {
      .side-nav { display: none; }
      .mobile-header { display: flex; }
      .main-content { margin-left: 0; }
      h1 { font-size: 2.4rem; }
      h2 { font-size: 1.9rem; }
      section { padding: 60px 0; }
    }
    @media (max-width: 768px) {
      .container { padding: 0 20px; }
      .glass-card { backdrop-filter: blur(12px); }
    }
    .highlight { color: var(--accent-cyan); }
    .text-purple { color: var(--accent-purple); }