/* roulang page: index */
:root {
      --primary: #7B2FBE;
      --primary-light: #A855F7;
      --accent: #00E5FF;
      --deep-bg: #0C0C0E;
      --light-bg: #F5F3F7;
      --card-bg: #ffffff;
      --text-dark: #1A1A1E;
      --text-light: #F0EDF5;
      --text-muted: #6B6A70;
      --border-light: #E8E3EF;
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-input: 6px;
      --shadow-card: 0 2px 16px rgba(123, 47, 190, 0.12);
      --shadow-deep: 0 0 30px rgba(168, 85, 247, 0.15);
      --font-head: "PingFang SC", "Microsoft YaHei", "Heiti SC", sans-serif;
      --font-body: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
      --font-number: "Inter", "SF Pro Display", system-ui, sans-serif;
      --transition-default: all 0.25s ease;
      --spacing-ctn: 40px;
    }

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

    html {
      scroll-behavior: smooth;
      scroll-padding-top: 80px;
    }

    body {
      font-family: var(--font-body);
      font-size: 16px;
      font-weight: 400;
      line-height: 1.75;
      color: var(--text-dark);
      background-color: #fff;
      -webkit-font-smoothing: antialiased;
    }

    @media (prefers-reduced-motion: reduce) {
      *,
      *::before,
      *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
      }
    }

    .container {
      width: 100%;
      max-width: 1280px;
      margin-inline: auto;
      padding-inline: var(--spacing-ctn);
    }

    img {
      display: block;
      max-width: 100%;
      height: auto;
    }

    a {
      text-decoration: none;
      color: inherit;
    }

    button,
    .btn {
      cursor: pointer;
      font-family: var(--font-head);
      font-weight: 700;
      border: none;
      outline: none;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      border-radius: var(--radius-btn);
      transition: var(--transition-default);
    }

    button:focus-visible,
    .btn:focus-visible,
    a:focus-visible {
      outline: 2px solid var(--accent);
      outline-offset: 2px;
    }

    h1, h2, h3 {
      font-family: var(--font-head);
      font-weight: 700;
      line-height: 1.3;
    }

    h1 {
      font-size: 48px;
    }
    h2 {
      font-size: 32px;
      margin-bottom: 1.25rem;
      color: var(--text-dark);
    }
    h3 {
      font-size: 20px;
      margin-bottom: 0.5rem;
            color: var(--text-dark);
    }

    /* ---------- 导航 ---------- */
    #nav {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 1000;
      transition: background 0.3s ease, backdrop-filter 0.3s ease;
      background: transparent;
    }
    #nav.scrolled {
      background: rgba(12, 12, 14, 0.8);
      backdrop-filter: blur(20px);
    }
    @supports not (backdrop-filter: blur(20px)) {
      #nav.scrolled {
        background: rgba(12, 12, 14, 0.95);
      }
    }
    .nav-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 72px;
    }
    .logo {
      font-family: var(--font-head);
      font-size: 1.8rem;
      font-weight: 800;
      color: #fff;
      letter-spacing: 1px;
      display: flex;
      align-items: center;
      gap: 8px;
      text-shadow: 0 0 10px rgba(168,85,247,0.7);
    }
    .logo-icon {
      display: inline-block;
      width:对角线28px;
      height: 28px;
      background: var(--primary-light);
      clip-path: polygon(50% 0%, 0% 100%, 100% 100%);
    }
    .nav-links {
      display: flex;
      gap: 32px;
      align-items: center;
    }
    .nav-links a {
      color: #F0EDF5;
      font-weight: 500;
      font-size: 0.95rem;
      transition: color 0.2s;
      position: relative;
      white-space: nowrap;
    }
    .nav-links a::after {
      content: "";
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 0%;
      height: 2px;
      background: var(--accent);
      transition: width 0.2s ease;
    }
    .nav-links a:hover {
      color: var(--accent);
    }
    .nav-links a:hover::after { width: 100%; }

    .btn-nav {
      background: transparent;
      border: 2px solid var(--accent);
      color: var(--accent);
      padding: 10px 22px;
      font-weight: 700;
      border-radius: var(--radius-btn);
      font-size: 0.9rem;
      transition: var(--transition-default);
    }
    .btn-nav:hover {
      background: rgba(0, 229, 255, 0.15);
      box-shadow: 0 0 14px rgba(0,229,255,0.4);
    }

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      background: transparent;
    }
    .hamburger span {
      width: 25px;
      height: 2.5px;
      background: #fff;
      transition: 0.3s;
    }

    /* 移动端抽屉 */
    .mobile-menu {
      position: fixed;
      top: 0; left: 0; width: 100%; height: 100vh;
      background: #0C0C0E;
      display: flex; flex-direction: column; align-items: center;
      justify-content: center; gap: 36px; z-index: 999;
      transform: translateX(100%);
      transition: transform 0.35s ease;
    }
    .mobile-menu.open { transform: translateX(0); }
    .mobile-menu a {
      font-size: 1.8rem; color: #F0EDF5; font-weight: 600;
    }