Set Background of All Boxes
.face.ac-back-side {
background: red !important;
}Set Background of Specific Boxes
If you have more than 3 boxes, copy lines 9-12, paste them into the snippet at line 13, and adjust as desired. The value you add to ‘nth-child()’ will correspond to the box when looking left to right.
/* FIRST BOX */
.ac-category:first-child .face.ac-back-side {
background: red !important;
}
/* SECOND BOX */
.ac-category:nth-child(2) .face.ac-back-side {
background: green !important;
}
/* THIRD BOX */
.ac-category:nth-child(3) .face.ac-back-side {
background: blue !important;
}