:root {
      --bg-color: #f9f9f9;
      --text-color: #333;
      --header-bg: #ffffff;
      --header-text: #007acc;
      --nav-link: #007acc;
      --hero-bg: linear-gradient(to right, #e0f7fa, #ffffff);
      --hero-text: #555;
      --card-bg: #ffffff;
      --card-border: #ddd;
      --card-title: #007acc;
      --footer-bg: #f0f0f0;
      --footer-border: #ddd;
      --footer-text: #777;
    }

    body.dark-mode {
      --bg-color: #1e1e1e;
      --text-color: #eaeaea;
      --header-bg: #2a2a2a;
      --header-text: #ffdd99;
      --nav-link: #ffd699;
      --hero-bg: #292929;
      --hero-text: #c2c2c2;
      --card-bg: #2f2f2f;
      --card-border: #3a3a3a;
      --card-title: #ffcc88;
      --footer-bg: #2a2a2a;
      --footer-border: #3a3a3a;
      --footer-text: #999;
    }

    body {
      margin: 0;
      font-family: 'Quicksand', sans-serif;
      background-color: var(--bg-color);
      color: var(--text-color);
      transition: background-color 0.3s, color 0.3s;
    }
    header {
      background-color: var(--header-bg);
      padding: 20px;
      text-align: center;
      box-shadow: 0 1px 5px rgba(0,0,0,0.05);
      position: relative;
    }
    header h1 {
      margin: 0;
      font-size: 2em;
      color: var(--header-text);
    }
    nav {
      margin-top: 10px;
    }
    nav a {
      margin: 0 15px;
      color: var(--nav-link);
      text-decoration: none;
      font-weight: 600;
    }
.main-nav {
  display: flex;
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
  gap: 15px;
}

.dropdown {
  position: relative;
  display: inline-block;
}

.dropdown-content {
  display: none;
  position: absolute;
  background-color: var(--card-bg);
  min-width: 240px;
  border: 1px solid var(--card-border);
  border-radius: 8px;
  box-shadow: 0 8px 16px rgba(0,0,0,0.1);
  padding: 10px 0;
  z-index: 1000;
}

.dropdown-content a {
  color: var(--nav-link);
  padding: 10px 20px;
  display: block;
  text-decoration: none;
  font-weight: 500;
}

.dropdown-content a:hover {
  background-color: #f0f8ff;
}

.dropdown:hover .dropdown-content {
  display: block;
}
    .hero {
      background: var(--hero-bg);
      padding: 60px 20px;
      text-align: center;
    }
    .hero h2 {
      font-size: 1.8em;
      margin-bottom: 10px;
    }
    .hero p {
      font-size: 1em;
      color: var(--hero-text);
    }
    .cards {
      display: flex;
      flex-wrap: wrap;
      justify-content: center;
      margin: 40px 20px;
      gap: 20px;
    }
    .card {
      background-color: var(--card-bg);
      border: 1px solid var(--card-border);
      border-radius: 12px;
      padding: 24px;
      width: 280px;
      box-shadow: 0 4px 8px rgba(0,0,0,0.04);
    }
    .card h3 {
      color: var(--card-title);
      margin-top: 0;
    }
    footer {
      text-align: center;
      padding: 20px;
      font-size: 14px;
      color: var(--footer-text);
      background-color: var(--footer-bg);
      border-top: 1px solid var(--footer-border);
    }
    .toggle-btn {
      position: absolute;
      top: 20px;
      right: 20px;
      background: none;
      border: none;
      color: var(--text-color);
      font-size: 20px;
      cursor: pointer;
      transition: color 0.3s;
      z-index: 100;
    }