CSS3 Transitions

At first, you must specify two things:

  • the CSS property you want to add an effect to and
  • the duration of the effect.
div {
    transition: opacity 0.5s;
    -webkit-transition: opacity 0.5s; /* Safari */

Then, you must specify :hover for the div element:

div:hover {
    opacity: 0.5;

Learning resources

  • Create slick HTML5 animations article.