Answer 1

A little change in JS:
*********************
function Se(){
var Ji = document.getElementById("Re");
Ji.style.animationName="Cri";
}
*********************
This will definitely work!:)

Answer 2

Where is the id "Re"?
You should specify it somewhere (for any tag), like if you want it on your button, you can do :

<button id="Re" onclick="Se()">Bi<button>

And, for the CSS, id's are defined using a "#" before it.

Answer 3

That's because you didn't put Cy in the @-webkit-keyframes part or Cri in the animation-name part.

Try implementing either of the two!

Answer 4

@Forge: Exactly what @Biraj said. The animationName property sets or returns a name for the @keyframes animation. Just animation would not do ^^