The rules for ink-c-button had states apply directly on the

.ink-c-button class and not bound to variations like

.ink-c-button:link. This led to bad styling in some circumstances, in

particular for active/hover styles on links.
Like other components, these are now specified as rules built upon the

top-level &-bound selector for the component.

Verified that this fixed active states on some buttons in Review Board.