Transition is key when transitioning from one value to another based on an event.
Take a look at the visibility setting for an element:
.two {
background-color: #9fa8da;
position: absolute;
visibility: hidden;
transition: visibility 3ms ease-in;
}
When a button is clicked, the visibility is changed to 'visible'
.two-show {
visibility: visible;
}
Unfortunately, there is no animation effect present.
Check out the Plnkr demo here: