Ensure a consistent use of fonts.

Previously we had a few locations that had slight differences, but
didn't need to. This commit also puts the IDE closer to the fonts
used on the main website.

Change-Id: I1668a6e9891f1de4bd25687abd575c11401c3969
Tidy logic that higlights the current day.

Change-Id: Ia975b3c5b5fefd628eb8e1cc7deddea48a1f17d6
Fix HTML validation issues.

These should mostly have no effect on any experience, but may tidy
things in IE. The most singificant fix here is the correction of
the closing tab of #proj-select-all, which managed to sneak through
in the recent UI changes (commit 14723083).

Change-Id: I35f58de04acdb38c9a6ae3b3aa287b931a7979b4
Fix a couple of comments.

Change-Id: I8da64c58bb5f448238df210f609e74e3b8152ae7