body {
    font-family: 'Segoe UI', Arial, sans-serif;
    margin: 0;
    background: linear-gradient(135deg, #667eea, #764ba2, #f0932b, #eb4d4b);
    background-size: 400% 400%;
    animation: gradient 20s ease infinite;
    color: white;
    min-height: 100vh;
}

@keyframes gradient {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

header {
    text-align: center;
    padding: 80px 20px 40px;
}

h1 { font-size: 3.5rem; margin: 0; text-shadow: 0 4px 10px rgba(0,0,0,0.4); }

.button-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 25px;
    padding: 40px;
    max-width: 1200px;
    margin: 0 auto;
}

.topic-btn {
    padding: 30px 20px;
    font-size: 1.4rem;
    background: rgba(255,255,255,0.15);
    border: 3px solid rgba(255,255,255,0.6);
    border-radius: 20px;
    text-align: center;
    text-decoration: none;
    color: white;
    transition: all 0.4s;
    backdrop-filter: blur(10px);
}

.topic-btn:hover {
    transform: translateY(-10px) scale(1.05);
    background: rgba(255,255,255,0.3);
    box-shadow: 0 20px 40px rgba(0,0,0,0.3);
}