How to make home page images grid and 2 grids per row in mobile view?

Site URL: https://rosylingerie.ca

Hi there,

Just wondering how to make the four photos which below my "shop now" button become grid style and 2 images per row in mobile view only? 

Thanks!

Add to Design > Custom CSS

/*Mobile-Homepage-2 columns */
@media screen and (max-width:767px) {
div#page-section-608d05398a421213d84d115c .span-3 {
    width: 50% !important;
    float: left !important;
}
}

Works perfect! Thanks @tuanphan