png opacity

#social img {
padding:4px 6px;
float:left;
}

#social a img {
opacity:.75;
-ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=75)";
filter:alpha(opacity=75);
}

#social a img:hover {
opacity:1;
-ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=100)";
filter alpha(opacity=100);
}