:root {
    --primary-color: #0d6efd;
    --secondary-color: #6c757d;
    --success-color: #198754;
    --danger-color: #dc3545;
    --warning-color: #ffc107;
    --info-color: #0dcaf0;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
}

.hero-section {
    background: linear-gradient(135deg, var(--primary-color), #4e73df);
    color: white;
}

.card {
    transition: transform 0.2s ease-in-out, box-shadow 0.2s ease-in-out;
    border: none;
    box-shadow: 0 0.15rem 1.75rem 0 rgba(58, 59, 69, 0.15);
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 0.5rem 2rem 0 rgba(58, 59, 69, 0.2);
}

.rating-stars {
    color: var(--warning-color);
}

.btn-primary {
    background-color: var(--primary-color);
    border-color: var(--primary-color);
}

.btn-primary:hover {
    background-color: #0b5ed7;
    border-color: #0a58ca;
}

.sidebar {
    min-height: calc(100vh - 56px);
    box-shadow: inset -1px 0 0 rgba(0, 0, 0, .1);
}

.sidebar .nav-link {
    color: #333;
    padding: 0.75rem 1rem;
}

.sidebar .nav-link.active {
    color: var(--primary-color);
    font-weight: 600;
}

.sidebar .nav-link:hover {
    color: var(--primary-color);
}

/* Material card styles */
.material-card .card-img-top {
    height: 200px;
    object-fit: cover;
}

.price-tag {
    font-size: 1.25rem;
    font-weight: bold;
    color: var(--success-color);
}

.free-badge {
    background-color: var(--success-color);
    color: white;
}

/* Cart styles */
.cart-item {
    border-bottom: 1px solid #dee2e6;
    padding: 1rem 0;
}

.cart-total {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .sidebar {
        position: static;
        height: auto;
    }
    
    .hero-section h1 {
        font-size: 2rem;
    }
}

/* Loading spinner */
.loading-spinner {
    display: inline-block;
    width: 2rem;
    height: 2rem;
    border: 0.25em solid currentColor;
    border-right-color: transparent;
    border-radius: 50%;
    animation: spinner-border 0.75s linear infinite;
}

@keyframes spinner-border {
    to { transform: rotate(360deg); }
}

/* Alert styles */
.alert {
    border: none;
    border-radius: 0.5rem;
}

.alert-danger {
    background-color: #f8d7da;
    color: #721c24;
}

.alert-success {
    background-color: #d1edff;
    color: #155724;
}