-webkit-filter: grayscale(50%);
-moz-filter: grayscale(50%);
-o-filter: grayscale(50%);
filter: grayscale(50%);
.gray {
-webkit-filter: grayscale(100%);
-moz-filter: grayscale(100%);
-o-filter: grayscale(100%);
filter: grayscale(100%);
}
map.panes.get('ground').getElement().classList.add('gray');