Use Include in CSS.

Question

Hello everyone I have User this code in css file(asp.net core razor).But not working this warning message display

 

.card-columns {

@include media-breakpoint-only(lg) {

column-count: 4;

}

@include media-breakpoint-only(xl) {

column-count: 5;

}

}

 

Please check and let me know it's working or not in CSS file