style.css now only imports the parts in order, after voice.css and
music.css as before, so the cascade is unchanged. Each cut sits between
top-level rules. Checked twice: the parts (minus the one-line header each
got) rebuild the old file byte for byte, and a browser loading the new
style.css ends up with the same 3,526 rules, in the same order, as it parses
from the old one. The largest part is 1,559 lines. Tests that read
style.css now read it with its imports filled in (test/coreCss.js), and the
theme contract test names the part each checked rule lives in.
