Hi everyone, there are improvements and changes coming to themes in Firefox, and you can read about them here.
It’s an improvement for some, and a death stroke for others. I will have to end my 18 years career of doing themes with Firefox 57 as the design of LCARStrek is impossible with the new scheme. It was great while it lasted, but I guess the new path of Firefox is incompatible with a 24th century look. 
Sometimes improvements to one person are not improvements to another. I am old and don’t like change so am not pleased, either…
Yes, the change impacts complete theme authors like kairo disproportionately. But it shouldn’t affect lightweight theme authors like MaDonna very much.