/* roulang page: index */
:root {
      --deep-purple: #1E0F2E;
      --aurora-green: #2EE6B0;
      --bg-dark: #0F0A1A;
      --card-bg: #1C1428;
      --light-bg: #F5F3F7;
      --text-white: #FFFFFF;
      --text-light: #F5F3F7;
      --text-body: #CBC3D9;
      --text-muted: #8B7FA8;
      --border-glow: rgba(46, 230, 176, 0.18);
      --border-active: rgba(46, 230, 176, 0.5);
      --shadow-card: 0 10px 28px rgba(0, 0, 0, 0.5);
      --shadow-hover: 0 18px 36px rgba(0, 0, 0, 0.6);
      --radius-card: 18px;
      --radius-btn: 40px;
      --font-display: 'Inter', 'SF Pro', 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
      --transition-smooth: all 0.25s ease;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    html {
      scroll-behavior: smooth;
      font-size: 16px;
    }
    body {
      font-family: var(--font-display);
      background-color: var(--bg-dark);
      color: var(--text-body);
      line-height: 1.6;
      display: flex;
      flex-direction: column;
      min-height: 100vh;
      overflow-x: hidden;
    }
    img {
      max-width: 100%;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: var(--transition-smooth);
    }
    button, .btn {
      cursor: pointer;
      font-family: inherit;
      font-weight: 600;
      border: none;
      background: none;
      transition: var(--transition-smooth);
    }
    .container {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 2rem;
    }
    /* 左侧竖向导航 (桌面端) */
    .side-nav {
      position: fixed;
      left: 0;
      top: 0;
      width: 260px;
      height: 100vh;
      background-color: #0F0A1A;
      display: flex;
      flex-direction: column;
      justify-content: space-between;
      padding: 2.5rem 1.8rem;
      border-right: 1px solid rgba(46, 230, 176, 0.18);
      z-index: 1000;
      box-shadow: 2px 0 18px rgba(0,0,0,0.6);
    }
    .brand-area {
      margin-bottom: 2.8rem;
    }
    .logo-text {
      font-size: 2.1rem;
      font-weight: 700;
      color: var(--aurora-green);
      letter-spacing: 0.5px;
      display: block;
      line-height: 1.2;
    }
    .logo-tagline {
      font-size: 0.75rem;
      color: var(--text-muted);
      margin-top: 0.4rem;
      font-weight: 400;
    }
    .nav-links {
      list-style: none;
      display: flex;
      flex-direction: column;
      gap: 1.6rem;
      margin-top: 2rem;
    }
    .nav-links li a {
      display: flex;
      align-items: center;
      gap: 0.7rem;
      font-size: 1rem;
      font-weight: 500;
      color: var(--text-body);
      padding: 0.5rem 0;
      position: relative;
      transition: color 0.2s;
    }
    .nav-links li a::before {
      content: '';
      position: absolute;
      left: -1.2rem;
      top: 50%;
      transform: translateY(-50%);
      width: 3px;
      height: 18px;
      background-color: transparent;
      border-radius: 4px;
      transition: background-color 0.2s;
    }
    .nav-links li a:hover,
    .nav-links li a.active {
      color: var(--aurora-green);
    }
    .nav-links li a:hover::before,
    .nav-links li a.active::before {
      background-color: var(--aurora-green);
    }
    .nav-footer {
      font-size: 0.7rem;
      color: var(--text-muted);
      margin-top: auto;
      opacity: 0.7;
    }
    /* 主内容区域 */
    .main-content {
      margin-left: 260px;
      width: calc(100% - 260px);
      background-color: var(--bg-dark);
    }
    /* 移动端顶部导航 */
    .mobile-nav {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 60px;
      background-color: #0F0A1A;
      border-bottom: 1px solid rgba(46,230,176,0.15);
      align-items: center;
      justify-content: space-between;
      padding: 0 1.5rem;
      z-index: 999;
    }
    .mobile-logo {
      font-weight: 700;
      font-size: 1.5rem;
      color: var(--aurora-green);
    }
    .hamburger {
      font-size: 1.8rem;
      color: var(--text-light);
      background: none;
      border: none;
    }
    .mobile-menu {
      display: none;
      flex-direction: column;
      background: #0F0A1A;
      position: fixed;
      top: 60px;
      left: 0;
      width: 100%;
      padding: 1.8rem 2rem;
      gap: 1.5rem;
      border-bottom: 1px solid rgba(46,230,176,0.2);
      z-index: 998;
    }
    .mobile-menu a {
      font-size: 1.1rem;
      color: var(--text-body);
      font-weight: 500;
    }
    .mobile-menu a:hover {
      color: var(--aurora-green);
    }
    /* 通用区块 */
    section {
      padding: 5rem 0;
    }
    .section-title {
      font-size: 2rem;
      font-weight: 600;
      color: var(--text-light);
      margin-bottom: 1rem;
      letter-spacing: -0.3px;
    }
    .btn-primary {
      background: var(--aurora-green);
      color: #0F0A1A;
      padding: 0.9rem 2.2rem;
      border-radius: var(--radius-btn);
      font-weight: 600;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 0.4rem;
      box-shadow: 0 0 16px rgba(46,230,176,0.35);
      transition: all 0.3s;
    }
    .btn-primary:hover {
      background: #1ED99E;
      box-shadow: 0 0 24px rgba(46,230,176,0.6);
      transform: translateY(-1px);
    }
    .card {
      background: var(--card-bg);
      border-radius: var(--radius-card);
      padding: 2rem;
      border: 1px solid var(--border-glow);
      box-shadow: var(--shadow-card);
      transition: var(--transition-smooth);
    }
    .card:hover {
      border-color: var(--border-active);
      box-shadow: var(--shadow-hover);
      transform: translateY(-5px);
    }
    @media (max-width: 1024px) {
      .side-nav {
        display: none;
      }
      .main-content {
        margin-left: 0;
        width: 100%;
      }
      .mobile-nav {
        display: flex;
      }
      .mobile-menu.open {
        display: flex;
      }
      section {
        padding: 3.5rem 0;
      }
      .container {
        padding: 0 1.5rem;
      }
    }
    @media (max-width: 768px) {
      .section-title {
        font-size: 1.7rem;
      }
      .card {
        padding: 1.5rem;
      }
    }