Ultrawide support

[evanonym0us]

the bottom is cut off

[Bios-Marcel]

Two things should be done here:

1. Let the toolbar take the empty space from under the chat input (just a change to grid-column-end: ...)
2. Somehow limit the width programmatically, I haven't really been able to do it with CSS before.

   This probably needs to handle window resizes as well. Can be done in the existing resize handler.
   The lobby should then be centered horizontally, as it will shrink in width, since we wouldn't want the chat to grow infinitely in width I assume.

It would be nice to be able to do this in a performant and bugfree way!

Edit: Number 1. is done