Base button is white on grey background

[bartaz]

Describe the bug

In 2.31.0 the background of base button was changed from transparent to white. It makes the button visible on lightgrey backgrounds (like MAAS) when it was not visible before.

Expected behavior

Context

This blocks MAAS update to 2.31.0: canonical/maas-ui#2736

[lyubomir-popov]

The base button used to be invisible on dark background, e.g. here:

Seems we need 2 things:

• transparent button that works on white and gray
• a button that works within dark elements, posibly not whie as that inverts the perception of primary-ness compared to the green

[bartaz]

@lyubomir-popov it may still be 1 thing, if the "transparent" base button works on dark backgrounds as well (with appropriate text and hover colors)