@media (max-width: 900px) {
    .container {
        grid-template-columns: 1fr;
    }
    
    .main-title {
        font-size: 1.8rem;
    }
    
    .form-row {
        grid-template-columns: 1fr;
    }
    
    .price-summary-box {
        grid-template-columns: 1fr;
        gap: 12px;
    }
}