Opacity mixins with fallback color

opacity.scss

/**
 * Translucent background colors with opaque text!
 * 
 * 		@example scss
 * 		@include background-opacity(#000, .5)
 * 
 *  @param {String} $color hexadecimal color
 *  @param {Integer} $opacity opacity value 0-1
 */
@mixin background-opacity( $color, $opacity: .5 ) {
	background: $color; // fallback
	background: rgba( $color, $opacity );
}

/**
 * Translucent border colors
 * 
 * 		@example scss
 * 		@include background-opacity(#000, .5)
 * 
 *  @param {String} $color hexadecimal color
 *  @param {Integer} $opacity opacity value 0-1
 */
@mixin border-opacity( $color, $opacity: .5 ) {
	border-color: $color; // fallback
	border-color: rgba( $color, $opacity );
}