Try adding this CSS:
@media (max-width: 840px) {
.site-content {
flex-direction: column;
}
.container .site-content .content-area {
width: auto;
}
.is-left-sidebar.sidebar, .is-right-sidebar.sidebar {
width: auto;
order: initial;
}
.wp-show-posts-columns, .wp-show-posts-inner {
margin-left: 0 !important;
margin-right: 0 !important;
}
.wp-show-posts-columns .wp-show-posts-single {
display: block;
width: 100%;
}
}
In the first line: @media (max-width: 840px) {
you can change the 840px
to 1024px
if you want to apply to the larger ipad.