Minor QoL fixes over a lunch break.

Requesting a merge of three minor commits:
* Added a forced, fixed `margin-right` on the expanded menu. This is to prevent the active level css styling overlapping with the menu toggle button in cases where the active level is the first or second level.
* Fixed some syntax regarding `board:` declerations. Mainly changing `{)` to `{}`. Didn't fix what wasn't broken, but it's nice to not cause confusion for future development.
* Enabled users to reference the `.table` element in their code. This allows users to write answers like `.table > plate`. The table element is filtered out if it is included in the element collection, which prevents the "Select all the things" level from selecting the table too.