Maintaining the final state at end of a CSS3 animation

I’m running an animation on some elements that are set to opacity: 0; in the CSS. The animation class is applied onClick, and, using keyframes, it changes the opacity from 0 to 1 (among other things).

Unfortunately, when the animation is over, the elements go back to opacity: 0 (in both Firefox and Chrome). My natural thinking would be that animated elements maintain the final state, overriding their original properties. Is this not true? And if not, how can I get the element to do so?

The code (prefixed versions not included):

@keyframes bubble {
    0%   { transform:scale(0.5); opacity:0.0; }
    50%  { transform:scale(1.2); opacity:0.5; }
    100% { transform:scale(1.0); opacity:1.0; }
}