css make image gray

1img {
2  filter: gray; /* IE6-9 */
3  -webkit-filter: grayscale(1); /* Google Chrome, Safari 6+ & Opera 15+ */
4  filter: grayscale(1); /* Microsoft Edge and Firefox 35+ */
5}
6
7/* Disable grayscale on hover */
8img:hover {
9  -webkit-filter: grayscale(0);
10  filter: none;
11}