/* roulang page: index */
/* ----- 设计变量 ----- */
    :root {
      --deep-space: #0A0E27;
      --bg-global: #060918;
      --cyan-electric: #00F0FF;
      --magenta-energy: #FF3CAC;
      --card-glass-bg: rgba(10, 20, 50, 0.45);
      --border-glow: rgba(0, 240, 255, 0.25);
      --text-primary: #F0F4FF;
      --text-secondary: #B0C7E9;
      --text-muted: #7A8BA8;
      --radius-card: 20px;
      --radius-pill: 30px;
      --radius-img: 12px;
      --shadow-card: 0 12px 32px rgba(0, 0, 0, 0.5), 0 0 1px rgba(0, 240, 255, 0.15);
      --shadow-glow: 0 0 20px rgba(0, 240, 255, 0.35);
      --transition-smooth: all 0.25s ease;
      --font-title: "PingFang SC", "Microsoft YaHei", "Inter", system-ui, -apple-system, sans-serif;
      --font-body: "PingFang SC", "Microsoft YaHei", "Inter", system-ui, sans-serif;
      --font-data: "DIN Alternate", "SF Mono", "Inter", monospace;
      --max-width: 1280px;
      --header-height: 80px;
    }

    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }

    body {
      font-family: var(--font-body);
      background-color: var(--bg-global);
      color: var(--text-primary);
      line-height: 1.6;
      scroll-behavior: smooth;
      -webkit-font-smoothing: antialiased;
    }

    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 28px;
    }

    /* 图片通用 */
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }

    a {
      text-decoration: none;
      color: inherit;
      transition: var(--transition-smooth);
    }

    /* 按钮系统 */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      font-family: var(--font-title);
      font-weight: 600;
      padding: 14px 36px;
      border-radius: var(--radius-pill);
      transition: all 0.3s cubic-bezier(0.23, 1, 0.32, 1);
      cursor: pointer;
      border: none;
      font-size: 16px;
      letter-spacing: 0.5px;
      gap: 8px;
    }

    .btn-primary {
      background: var(--cyan-electric);
      color: var(--deep-space);
      box-shadow: 0 8px 24px rgba(0, 240, 255, 0.45);
    }

    .btn-primary:hover {
      box-shadow: 0 0 40px rgba(0, 240, 255, 0.7);
      transform: scale(1.04);
      background: #33f5ff;
    }

    .btn-outline {
      background: transparent;
      border: 1.5px solid var(--cyan-electric);
      color: var(--cyan-electric);
      box-shadow: 0 0 12px rgba(0, 240, 255, 0.15);
    }

    .btn-outline:hover {
      background: rgba(0, 240, 255, 0.08);
      border-color: #66f7ff;
      box-shadow: 0 0 26px rgba(0, 240, 255, 0.4);
      color: white;
    }

    /* 头部导航 */
    .site-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 1000;
      height: var(--header-height);
      background: transparent;
      transition: background 0.35s ease, backdrop-filter 0.35s ease, box-shadow 0.35s ease;
      display: flex;
      align-items: center;
    }

    .site-header.scrolled {
      background: rgba(6, 9, 24, 0.88);
      backdrop-filter: blur(22px);
      box-shadow: 0 6px 24px rgba(0, 0, 0, 0.3);
      border-bottom: 1px solid rgba(0, 240, 255, 0.25);
    }

    .header-inner {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 28px;
    }

    .logo {
      font-family: var(--font-title);
      font-size: 28px;
      font-weight: 700;
      letter-spacing: 1px;
      color: white;
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .logo i {
      color: var(--cyan-electric);
      font-size: 30px;
    }
    .logo span {
      background: linear-gradient(135deg, #ffffff 0%, #ccf0ff 100%);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      background-clip: text;
    }

    .nav-links {
      display: flex;
      gap: 36px;
      align-items: center;
      font-weight: 500;
      color: #E0E8FF;
    }

    .nav-links a {
      position: relative;
      padding: 8px 0;
      font-size: 16px;
    }

    .nav-links a::after {
      content: '';
      position: absolute;
      width: 0%;
      height: 2px;
      bottom: 0;
      left: 0;
      background: var(--cyan-electric);
      transition: width 0.3s ease;
      box-shadow: 0 0 10px var(--cyan-electric);
    }

    .nav-links a:hover {
      color: white;
    }
    .nav-links a:hover::after {
      width: 100%;
    }

    .mobile-menu-toggle {
      display: none;
      background: none;
      border: none;
      color: white;
      font-size: 26px;
      cursor: pointer;
    }

    /* 移动端底部胶囊导航 (默认隐藏) */
    .mobile-bottom-nav {
      display: none;
      position: fixed;
      bottom: 16px;
      left: 50%;
      transform: translateX(-50%);
      background: rgba(8, 12, 28, 0.9);
      backdrop-filter: blur(24px);
      border: 1px solid rgba(0, 240, 255, 0.25);
      border-radius: 40px;
      padding: 8px 20px;
      z-index: 999;
      box-shadow: 0 12px 28px rgba(0,0,0,0.6);
    }
    .mobile-bottom-nav a {
      color: #b0c7e9;
      margin: 0 12px;
      font-size: 18px;
      transition: 0.2s;
    }
    .mobile-bottom-nav a.active {
      color: var(--cyan-electric);
      text-shadow: 0 0 10px var(--cyan-electric);
    }

    /* 板块间距 */
    section {
      padding: 100px 0;
      position: relative;
    }

    .section-title {
      font-size: 36px;
      font-weight: 700;
      margin-bottom: 16px;
      font-family: var(--font-title);
      color: white;
      letter-spacing: -0.3px;
    }
    .section-sub {
      color: var(--text-secondary);
      font-size: 18px;
      margin-bottom: 48px;
      max-width: 640px;
    }