You could try something like this:
@media (max-width: 768px) {
#wpsp-57068.wp-show-posts-columns .wp-show-posts-single {
width: 50%;
}
#wpsp-57068.wp-show-posts-columns {
margin-left: -2em !important;
}
#wpsp-57068.wp-show-posts-columns .wp-show-posts-inner {
padding-left: 2em;
}
}
You can add as many selectors to each block as you need, you just need to update the list ID for each one.
Alternatively, give the lists a custom class like two-column-mobile
and use that .two-column-mobile
in place of #wpsp-57068
.