body { font-family: sans-serif; background-color: #f9f9f9; padding: 20px; }
nav { display: flex; justify-content: space-between; align-items: center; padding: 10px 0; }
.shop-catalog { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 20px; }
.product-card, .cart-item { background: white; border: 2px solid #000; border-radius: 15px; padding: 20px; text-align: center; }
.nav-btn { background: #007bff; color: white; border: none; padding: 10px 20px; border-radius: 8px; cursor: pointer; }
.buy-btn { background: #28a745; color: white; padding: 15px 30px; border: none; border-radius: 8px; margin-top: 20px; cursor: pointer; }
#ui-notification {
    position: fixed;
    top: 20px;
    right: 20px;
    background-color: #333;
    color: white;
    padding: 15px 20px;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.2);
    z-index: 1000;
    font-family: sans-serif;
    animation: fadeIn 0.5s;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}
/* Base button style */
.add-btn {
    transition: background-color 0.3s ease, transform 0.1s;
}

/* Style when the item is added */
.add-btn.added {
    background-color: #28a745; /* Green for success */
    color: white;
    cursor: default;
}

.add-btn:active {
    transform: scale(0.95); /* Slight press animation */
}