style.scss

// To Create
@mixin size ($point) {
	@if $point == large {
		@media screen and (max-width: 1086px) {
			@content;
		}
	}
	@if $point == medium {
		@media screen and (max-width: 850px) {
			@content;
		}
	}
	@if $point == small {
		@media screen and (max-width: 528px) {
			@content;
		}
	}
}

// To Use
@include size(medium) {
  background: red;
}