Using CSS rgba() values for background-color in IE6+

You can use rgba values for background colors in IE6-9 with a simple Microsoft filter in your CSS. You can even find an amazing interactive tool to help you generate all this code here: www.css3please.com

.black-semi-transparent {
  background-color: transparent;
  background-color: rgba(0, 0, 0, 0.5);  /* FF3+, Saf3+, Opera 10.10+, Chrome, IE9 */
            filter: progid:DXImageTransform.Microsoft.gradient(startColorstr=#7F000000,endColorstr=#7F000000); /* IE6–IE9 */
            zoom: 1;
}