.class { background: rgba(0,0,0,.5); filter: progid:DXImageTransform.Microsoft.gradient(startColorstr="#7F000000",endColorstr="#7F000000");}
:root .class { filter: none;} /* IE9 */
with Sass, you can use:
.class { background: rgba(0,0,0,.5); filter: progid:DXImageTransform.Microsoft.gradient(startColorstr="#{ie-hex-str($color)}",endColorstr="#{ie-hex-str($color)}");}
converter: kilianvalkhof
