Hello,
Please add this code into custom.css file:
@media (max-width: 767px) {.one-half {
width: 100% !important;
}}
To create custom.css you need rename default.custom.css into custom.css that is located in wp-content/themes/blanco via FTP. Then enable it in wp-admin panel > Theme Settings > tick “Enable Custom CSS”.
Regards,
Eva Kemp.