Raised buttons and fabs should increase elevation on hover

[saunandrea]

Bug, feature request, or proposal:

Feature Request: Hover effect on Flat, Raised and FAB Buttons

What is the expected behavior?

Button gets slightly darker when hovering.

What is the current behavior?

No CSS change on hover.

[jelbourn]

Flat buttons definitely wouldn't do this (since they're eponymously flat), but raised buttons and fabs should

[saunandrea]

@jelbourn I don't know material design well but I would expect there to always be some type of hover animation. Just a little affordance that it is a button and is active, not necessarily a change in the drop shadow.

[sandrotonon]

@jelbourn Even a flat button should have a hover effect, as you can see here.

[atiris]

@jelbourn Or, as you can see directly on material.io web.
Can you assigne someone on this?