Hi There,
#1] Please add the following CSS under Customizer > Custom > Global CSS:
img.grayscale {
filter: gray; /* IE6-9 */
filter: grayscale(1); /* Microsoft Edge and Firefox 35+ */
-webkit-filter: grayscale(1); /* Google Chrome, Safari 6+ & Opera 15+ */
}
/* Disable grayscale on hover */
img.grayscale:hover {
filter: none;
-webkit-filter: grayscale(0);
}
#2] After that add the grayscale CSS class to the class field of your images:
http://i.imgur.com/lC2olKW.png
Hope it helps 🙂