Fix issues with new way of displaying the topic

- Removed bottom indentation of body_home from themes based in the
simplified family

- The overflow: hidden; is only required in Nox, in other themes it
messes with the timestamp and has been removed.

- Use a different method for scrolling to the bottom of the chat, that
works even if the scroll has to occur in an element instead of body.
Merge pull request #477 from xlexi/master

Fix issues with new way of displaying the topic