Gray Scale with CSS with Cross Bowser Support

img {
filter: gray; /* IE6-9 */
-webkit-filter: grayscale(1); /* Google Chrome, Safari 6+ & Opera 15+ */
filter: grayscale(1); /* Microsoft Edge and Firefox 35+ */
}

/* Disable grayscale on hover */
img:hover {
-webkit-filter: grayscale(0);
filter: none;
}