#add this code in responsive css
@media only screen and (max-width: 767px) {
/*CART THUMBNAIL FIX*/
.woocommerce-cart input#coupon_code {
min-width: 50% !important;
margin-bottom: 2%;
}
.woocommerce-cart td.product-thumbnail {
display: block !important;
}
.woocommerce-cart td.product-thumbnail:before {
display: none;
}
.woocommerce-cart td.product-thumbnail a img {
display: block;
width: 45px !important;
}
}