@mixin bg-opacity($color, $opacity: 1) { background: $color; /* The Fallback */ background: rgba($color, $opacity); } // Progress bars @mixin progress-variant($color) { background-color: $color; &[value]::-webkit-progress-value { background-color: $color; } &[value]::-moz-progress-bar { background-color: $color; } // IE10+, Microsoft Edge &[value]::-ms-fill { background-color: $color; } // IE9 @media screen and (min-width:0\0) { .progress-bar { background-color: $color; } } }