#ecommerce_cheque_instructions {
    height: 150px;
    width: 400px;
    color: #777;
    padding: 5px 8px;
    margin: 0 0 -5px;
}

@media (max-width: 800px) {
    #ecommerce_cheque_instructions {
        width: 300px !important;
        max-width: 90% !important;
    }
}