You have to chave line number 12557 in your style.css. Go to your style.css file and search for the code bellow and delete it.
.woocommerce #content div.product div.images, .woocommerce div.product div.images, .woocommerce-page #content div.product div.images, .woocommerce-page div.product div.images {
width: 50% !important;
}
Is your theme really responsive? I think your theme have a big issue with responsive.