Is it possible to change the animation keyframe attributes by making inline adjustments.
Take for example
@-moz-keyframes slidein { from {
as @Zetura said the best way to do it is to forget the "to" property and it will take the default value of the width or height or any thing you put it to the as example for me its work :
@keyframes slideInUp { 0% { height: 0px; } }