* { margin: 0; padding: 0; box-sizing: border-box; }
    body {
      font-family: 'Arial', sans-serif;
      background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
      min-height: 100vh;
      padding: 20px;
    }
    .container {
      max-width: 900px;
      margin: 0 auto;
      background: rgba(255, 255, 255, 0.95);
      border-radius: 20px;
      padding: 40px;
      box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
      backdrop-filter: blur(10px);
    }
    .header {
      text-align: center;
      margin-bottom: 40px;
    }
    .title {
      font-size: 2.5rem;
      color: #2c3e50;
      margin-bottom: 10px;
      font-weight: bold;
    }
    .subtitle {
      font-size: 1.2rem;
      color: #7f8c8d;
      margin-bottom: 30px;
    }
    .topics-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
      gap: 20px;
      margin-top: 20px;
    }
    .back-button {
      background: linear-gradient(45deg, #e74c3c, #c0392b);
      color: white; padding: 12px 25px; border-radius: 25px;
      text-decoration: none; margin-bottom: 30px; display: inline-block;
    }
    .topic-card {
      background: white;
      border-radius: 15px;
      padding: 25px;
      box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
      border-left: 5px solid #8e44ad;
      transition: all 0.3s ease;
      text-decoration: none;
      color: inherit;
      display: block;
    }
    .topic-card:hover {
      transform: translateY(-5px);
      box-shadow: 0 15px 30px rgba(0, 0, 0, 0.15);
      border-left-color: #6c3483;
    }
    .topic-icon { font-size: 2.5rem; margin-bottom: 15px; display: block; }
    .topic-title { font-size: 1.4rem; color: #2c3e50; font-weight: bold; margin-bottom: 10px; }
    .topic-description { color: #7f8c8d; font-size: 0.95rem; line-height: 1.5; }
    .topic-level { background: #8e44ad; color: white; padding: 4px 8px; border-radius: 12px; font-size: 0.8rem; font-weight: bold; display: inline-block; margin-top: 10px; }
    @media (max-width:768px){
      .container   { padding:25px; }
      .title       { font-size:2rem; }
      .topics-grid { grid-template-columns:1fr; gap:15px; }
      .topic-card  { padding:20px; }
    }