:root {
      --primary: #2980b9;
      --secondary: #6dd5fa;
      --highlight: #f39c12;
    }

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

    body {
      font-family: 'Roboto', sans-serif;
      background: linear-gradient(135deg, #6dd5fa, #ffffff);
      min-height: 100vh;
      display: flex;
      flex-direction: column;
    }

    nav {
      background: linear-gradient(to right, #2980b9, #6dd5fa);
      padding: 15px 40px;
      color: white;
      display: flex;
      justify-content: space-between;
      align-items: center;
      box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    }

    nav h1 {
      font-size: 24px;
      font-weight: 700;
    }

    nav ul {
      display: flex;
      gap: 20px;
    }

    nav ul li {
      list-style: none;
    }

    nav ul a {
      color: white;
      text-decoration: none;
      font-weight: 500;
      transition: color 0.3s;
    }

    nav ul a:hover {
      color: var(--highlight);
    }

    .container {
      flex: 1;
      max-width: 800px;
      margin: 60px auto;
      padding: 30px;
      background: white;
      border-radius: 16px;
      box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
      text-align: center;
      animation: fadeIn 1s ease-in;
    }

    h2 {
      margin-bottom: 25px;
      color: #2c3e50;
    }

    ul.baitap {
      list-style: none;
      padding: 0;
    }

    ul.baitap li {
      margin: 15px 0;
    }

    ul.baitap a {
      display: inline-block;
      padding: 12px 25px;
      border-radius: 8px;
      background: var(--primary);
      color: white;
      text-decoration: none;
      font-size: 18px;
      font-weight: 500;
      transition: all 0.3s ease;
    }

    ul.baitap a:hover {
      background: var(--highlight);
      transform: scale(1.05);
    }

    footer {
      text-align: center;
      padding: 20px;
      font-size: 14px;
      color: #666;
    }

    @keyframes fadeIn {
      from {
        opacity: 0;
        transform: translateY(20px);
      }
      to {
        opacity: 1;
        transform: translateY(0);
      }
    }

    /* Responsive */
    @media (max-width: 600px) {
      nav {
        flex-direction: column;
        align-items: flex-start;
      }

      nav ul {
        flex-direction: column;
        margin-top: 10px;
        gap: 10px;
      }

      .container {
        margin: 30px 10px;
        padding: 20px;
      }

      ul.baitap a {
        width: 100%;
      }
    }