Created by: Snurppa
Buttons that do not specify any variant, did not have all CSS variables defined, such as --#{$prefix}btn-hover-bg. Those were defined only by the button-variant mixins.
Variables of this PR mimic what the button-variant mixins would do (more or less), but applied to so-called "default" .btn (my own terminology invention) with transparent background and, for example, :hover background shaded against $body-bg.
Should not affect anything else, but those using .btn without accompanying .btn-#{$variant}, which most likely is rare...?
Our project happens to use buttons in this obscure way, and noticed something changed in v5.2 release regarding the :hover behavior of our "naked" buttons
Any comments are welcome. Also, I understand if this is seen as unnecessary. But my Inspector would be free of grayish --bs-btn-hover-bg is not defined stains