Text drop-down selected and hover state

[tmickel]

Currently, it's some % darker, and with the standard Google closure checkbox.

Note that in the current implementation, the checkmark doesn't follow scroll (bad) and is visible in the old spot after a new one is selected. Haven't investigated too much, but this might necessitate moving away from the Closure menu widget. @rachel-fenichel

[tmickel]

Resolved the issues above - happy with it currently.