Vertical toolbar items should have no border radius

[oleq]

This line used to have a higher specificity than the default .ck-button. Since the .ck class has been introduced, this rule has lower specificity and hence the toolbar items look as follows:

Quick fix:

.ck.ck-toolbar.ck-toolbar_vertical > .ck

instead of

.ck.ck-toolbar.ck-toolbar_vertical > *

cc @dkonopka