Control CP matrix layout with CSS Is it possible to control the Matrix layout with CSS within the CP?

The Rich Text fields I have are currently displaying like this:



But I'd like this specific field to look something like this:



I'd like to avoid using a plugin if possible.
Unfortunately not. To do that kind of change your best bet would be to use CPCSS. It's a plugin but really only just provides you with a way to inject custom styles or a stylesheet for use in the control panel. It's well maintained by a responsible author so I don't see any reason to worry about that one.