rgbas.scss

// Provides support for rgba color also for old Internet Explorer versions (>=6; <=8)

@mixin background-color-rgba($fullColor) {
	$r: red($fullColor);
	$g: green($fullColor);
	$b: blue($fullColor);
	$a: round((alpha($fullColor))*255);
	$argbHex: decToHex($a)+decToHex($r)+decToHex($g)+decToHex($b);
	$msFilter: quote("progid:DXImageTransform.Microsoft.gradient(startColorstr=#"+$argbHex+", endColorstr=#"+$argbHex+")");
	// Web browsers that does not support RGBa
	background: rgb($r, $g, $b);
	// IE9 and modern browsers
	background: $fullColor;
	.ie8 &, .ie7 &, .ie6 &  {
		background: none;
		-ms-filter: $msFilter;
		filter: unquote($msFilter);
		zoom: 1;
		width: 100%;
	}
}

@function decToHex($d) {
	$hexVals: "A" "B" "C" "D" "E" "F";
    $base: 16;
    $quotient: $d;
    $result: "";
    @if $d == 0 {
        $result: "00";
    }
    @while $quotient != 0 {
        $mod: $quotient % $base;
        $quotient: floor($quotient / $base);
        @if $mod > 9 {
            $mod: nth($hexVals, $mod - 9);
        }
        @if $d < $base {
            $result: "0" + $mod;
        } @else {
            $result: $mod + $result;
        }
    }
    @return $result;
}