Now you can copy and paste code out of file views without skipped lines creeping in.

This removes the hack wherein we scrunched up our line height to make up for extra lines inserted in the <pre>.
Make alignment of line numbers and lines of code more elegant. Tighten up line height in file views a little, too.

Stop screwing around with padding and margins, wishing things would line up. Both line numbers and lines of code now get no padding or margin, and we explicitly align the baselines. (MDN says that's the default for vertical-align, but really it's "middle" according to the computed style pane.)

Remove pointless styling of th elements which are hidden anyway.

Search results still have slightly looser leading than file views. That's intentional, since snippet lines have nothing to do with each other: snuggling them up to reveal structure as in file views doesn't make sense.