* { 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, #000000);
        color:white; padding:12px 25px; border-radius:25px;
        text-decoration:none; margin-bottom:30px; display:inline-block;
    }

    .back-button:hover {
         background: linear-gradient(45deg, #080222);
    }

    .topic-card {
        background: white;
        border-radius: 15px;
        padding: 25px;
        box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
        border-left: 5px solid #e74c3c;
        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: #c0392b;
    }
    .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: #e74c3c; 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; }
    }