Skip asset processing for data uri in css

Editor assessment

A restrained, correct fix message. The subject is imperative and specific — skipping asset processing for data URIs in CSS names both the trigger and the affected file type — with no trailing period and reasonable length; a (css) scope would have been a free improvement. The footer 'fix #66' sits after a proper blank line, and while 'Fixes: #66' is the more canonical trailer spelling, this form is widely recognized and keeps the issue reference out of the subject. The absent body is acceptable: the change is small and the subject covers the behavior, though a note on the symptom (double-processing corrupting data URIs, presumably) would help. Type choice and patch-level semantics are right. Nothing here would trip up tooling — a quietly well-formed commit.