Creating a mixin to set a div to transparent requires special attention to evaluate a variable in a string. The -ms-filter line must be quoted and should include the result of a calculation ($amount * 100). How can I successfully incorporate this into my mixin?
@mixin transparent( $amount: .7, $color: black ) {
background: $color;
-ms-filter: progid:"DXImageTransform.Microsoft.Alpha(Opacity=$amount * 100)";
filter: alpha(opacity= $amount * 100);
opacity: $amount;
}