guitehub

.grayscale-hover {
  filter: grayscale(100%);
  -o-filter: grayscale(100%);
  -moz-filter: grayscale(100%);
  -webkit-filter: grayscale(100%);
  transition: .4s ease-in-out;
  -o-transition: .4s ease-in-out;
  -moz-transition: .4s ease-in-out;
  -webkit-transition: .4s ease-in-out;
}