What’s even more weird is that the generated CSS is still defining the “mobile content padding” as different than the desktop padding:
@media (max-width: 768px)
.separate-containers .inside-article, .separate-containers .comments-area, .separate-containers .page-header, .separate-containers .paging-navigation, .one-container .site-content, .inside-page-header {
padding: 30px;
}
Looks like there might be a bug with the customizer not rendering this option anymore.