Copy and paste the following code into the "Page Header HTML:" text box in the apps display settings:
<style>
@media screen and (max-width: 641px) {
#col-main {
width: 96% !important;
margin-left: 10px;
margin-right: 10px;
}
}
</style>
This may not work perfectly for all themes, and if you needed further changes than feel free to let us know by contacting our Support Wizards here.