img.logo-gray-scale  {
    
filter: url("data:image/svg+xml;utf8,<svg xmlns=\'http://www.w3.org/2000/svg\'><filter id=\'grayscale\'><feColorMatrix type=\'matrix\' values=\'0.3333 0.3333 0.3333 0 0 0.3333 0.3333 0.3333 0 0 0.3333 0.3333 0.3333 0 0 0 0 0 1 0\'/></filter></svg>#grayscale"); /* Firefox 10+, Firefox on Android */
filter: gray; /* IE6-9 */
-webkit-filter: grayscale(100%); /* Chrome 19+, Safari 6+, Safari 6+ iOS */
-moz-filter: grayscale(100%);
-ms-filter: grayscale(100%); 
-o-filter: grayscale(100%);
filter: progid:DXImageTransform.Microsoft.BasicImage(grayscale=1);
    /* Element must "hasLayout"! */
    zoom: 1;
}
.simple-logo:hover .logo-gray-scale{
 filter: url("data:image/svg+xml;utf8,<svg xmlns=\'http://www.w3.org/2000/svg\'><filter id=\'grayscale\'><feColorMatrix type=\'matrix\' values=\'1 0 0 0 0, 0 1 0 0 0, 0 0 1 0 0, 0 0 0 1 0\'/></filter></svg>#grayscale");
-webkit-filter: grayscale(0%);
-moz-filter: grayscale(0%);
-ms-filter: grayscale(0%); 
-o-filter: grayscale(0%);
}