I made it more Medium-esque

This is  the first project I've contributed to on GitHub, so please bare with me.

I fixed the toolbar's behavior when it is going from an inactive to an active state. Where it used to fade in while animating from its previous position, it now fades in above its new position.

I slightly changed the stylesheet, adding a slight gradient to the background, changing the active icon colors, changing the box-shadows, and adding a -webkit- prefix to the transitions.

I also added underline to the formatDict variable in the updateState function.

Thanks,
James