How to return the arrows to the slider on the mobile version?

Question

GitHub

Good afternoon!
I understand that the information may not be complete, but I will be glad to any advice.
In general, there is a slider, a small scroll of goods, everything works fine on the PC, on the mobile version the arrows disappear and only 1 slider element is shown, although if you move your finger, the elements further are shown. The arrow just disappears and the user does not understand what can be scrolled.
Arrows are created
.fa-angle-left:before {
content: "\f104";
}
:after, :before {
-webkit-box-sizing: border-box;
-moz-box-sizing: border-box;
box-sizing: border-box;
}
The block is nested in a div
Maybe someone can immediately tell where to dig?)