Removed unused aspect ratio mixin

stylesheets/_mixins.scss

@@ -1,20 +1,3 @@
-@mixin aspect-ratio($width, $height) {
-  position: relative;
-  &:before {
-    display: block;
-    content: "";
-    width: 100%;
-    padding-top: ($height / $width) * 100%;
-  }
-  > .inner {
-    position: absolute;
-    top: 0;
-    left: 0;
-    right: 0;
-    bottom: 0;
-  }
-}
-
 @mixin color-svg($svg, $color) {
     -webkit-mask: url($svg) no-repeat center;
     -webkit-mask-size: 100%;