Hide extra rooms when you have too many in Conpherence

Summary: This probably stopped working when we switch to a standard nav view. Re-scope CSS. Also make scrolling to last room a little easier.

Test Plan: Make 20 rooms, see the old ones vanish. Click See More, scroll to bottom, click last room

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D16656