Change controls style with CSS in OpenLayers 3.5.0

Question

My question is simple: It is possible to change the controls button styles with a CSS ? And if I do that, Can I don't load the CSS of OpenLayers ?

Answer 1

And the answer is also simple:

.ol-control button{ 
    background-color: rgba(40, 40, 40, 0.85) !important;
}

The !important is to overwrite the default style.

And no, do load their css. It is too much to substitute.