I had an issue to validate correct settings while Zone creation:
Network → Firewall → Zones → add/edit dialog window → field “Allow forward from source zones” uses list of checkboxes “zone: lan”.
Unfortunately the text “lan” uses white font color and the background value “rgb(var(–clr-border-error-50))” does not exist therefore the background is also white.
White text on white background is not possible to read 
I guess the correct value should be “–clr-error-50”… Does anyone experienced the same issue?
(using latest RUTX_R_00.07.13.3)