Hi,
Go to the Appearance -> Editor -> style.css
and paste below CSS code at the end of style.css file and click on update file button.
.woocommerce #content div.product div.images, .woocommerce div.product div.images, .woocommerce-page #content div.product div.images, .woocommerce-page div.product div.images, .woocommerce #content div.product div.summary, .woocommerce div.product div.summary, .woocommerce-page #content div.product div.summary, .woocommerce-page div.product div.summary { float:none; width:auto }
Regards
Grace Themes