Improve display on narrow screens.

This adds narrow.css, which stacks the "previous stats" box on top of
the "vote" box.

Use super fancy CSS media rules to trigger narrow.css only for screens
narrower than 1050px (experimentally determined to be about where things
start overlapping).

Unrelated, but bundled for laziness: Also add some extra padding to
per-element MFK titles so they always have enough space for 2 lines of
text. This means the rest of the screen doesn't move around depending on
now long the MFK titles are.