zmcnees

Thank you so much, this is SO incredibly helpful. 

@zmcnees Simply add the section ID, followed by a comma, to the code for each section where you want to enable two columns on mobile.

@zmcnees You're correct. You can remove the code from my previous comment to the following:
@media only screen and (max-width: 767px) { section[data-section-id="664cae16d2d73441a627baec"], section[data-section-id="66abc88dce511c7273082f35"] { .user-items-list .user-items-list-item-container { grid-template-columns: 1fr 1fr !important; } } }  

Thank you so much!!

@zmcnees You can add this code in Website > Pages > Website Tools > Custom CSS
@media only screen and (max-width: 767px) { .user-items-list .user-items-list-item-container { grid-template-columns: 1fr !important; } }