13
You'll have to use multiple browser specific property (moz-transition, webkit-transition...)
A good explanation of how to use them is there: https://developer.mozilla.org/en/CSS/CSS_transitions
for your case that'll be something like
.showUp {
transition:height .5s;
height:50px;
overflow:hidden;
}
.showLeft {
transition:width .5s;
width:0px
overflow:hidden;
}
.showUp.hideUp {
height:0px
}
.showLeft.hideLeft {
width:50px
}
And toggling hideUp and hideLeft classes to do a transition.