body {
    font-family: 'Poppins', sans-serif;
    background-color: #f8f9fa;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}
main { flex: 1; }

.bg-gradient-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.hero-section {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.subject-card {
    transition: transform 0.3s, box-shadow 0.3s;
}
.subject-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0,0,0,0.1) !important;
}

.card {
    border: none;
    border-radius: 12px;
}

.btn {
    border-radius: 8px;
}

.nav-tabs .nav-link {
    color: #6c757d;
    font-weight: 500;
}
.nav-tabs .nav-link.active {
    color: #667eea;
    font-weight: 600;
}

.content-text {
    line-height: 1.8;
    font-size: 1.05rem;
}

.form-check-input:checked {
    background-color: #667eea;
    border-color: #667eea;
}

#timer {
    font-family: monospace;
    padding: 8px 16px;
}

@media (max-width: 768px) {
    .display-4 { font-size: 2rem; }
    .display-3 { font-size: 2.5rem; }
}