https://bugzilla.redhat.com/show_bug.cgi?id=1546459
--- Comment #7 from Robert-André Mauchin zebob.m@gmail.com --- File a bug against https://apps.fedoraproject.org/packages/nodejs-csso/bugs and make it block this one. Try to bother jsmith on IRC or mail him about it.
FYI you just need to relax the dep in %prep:
%nodejs_fixdep css-tree
You could send a PR.