Refresh checks and radios styling

Retry of !1162 (closed)

Plus ...

... a fix for the missing image error

(gtk3-widget-factory:5234): Gtk-WARNING **: 10:27:10.692: Theme parsing error: gtk.css:1176:74: Not a valid image

I introduced in this line

f261b41d

when I didn't use "image(...)" for the hover color of the light variant check/radios.