As King King said, you must add the browser specific prefix. This should cover most browsers:
@keyframes flickerAnimation {_x000D_
0% { opacity:1; }_x000D_
50% { opacity:0; }_x000D_
100% { opacity:1; }_x000D_
}_x000D_
@-o-keyframes flickerAnimation{_x000D_
0% { opacity:1; }_x000D_
50% { opacity:0; }_x000D_
100% { opacity:1; }_x000D_
}_x000D_
@-moz-keyframes flickerAnimation{_x000D_
0% { opacity:1; }_x000D_
50% { opacity:0; }_x000D_
100% { opacity:1; }_x000D_
}_x000D_
@-webkit-keyframes flickerAnimation{_x000D_
0% { opacity:1; }_x000D_
50% { opacity:0; }_x000D_
100% { opacity:1; }_x000D_
}_x000D_
.animate-flicker {_x000D_
-webkit-animation: flickerAnimation 1s infinite;_x000D_
-moz-animation: flickerAnimation 1s infinite;_x000D_
-o-animation: flickerAnimation 1s infinite;_x000D_
animation: flickerAnimation 1s infinite;_x000D_
}
_x000D_
<div class="animate-flicker">Loading...</div>
_x000D_
~ Answered on 2014-06-01 22:16:53