.KeyTips__popup {
  -ms-filter: "progid:DXImageTransform.Microsoft.Alpha(opacity=80)";
}

* html .KeyTips__popup { filter: progid:DXImageTransform.Microsoft.Alpha(opacity=80); }
*:first-child+html .KeyTips__popup { filter: progid:DXImageTransform.Microsoft.Alpha(opacity=80); }