.img-grayscale {
    filter: grayscale(100%);
    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 */
}

.img-transparent {
    filter: alpha(opacity=50); /* IE 5-7 */
    -ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=50)"; /* IE 8 */
    -moz-opacity: 0.5; /* Netscape */
    -khtml-opacity: 0.5; /* Safari 1.x */
    opacity: 0.5; /* Good browsers */
}