Very old post, but I see this still hasn't been resolved, so I'm keeping it alive!
Hello! So lately I have noticed that the 'preview your signature' is a lot smaller that what it looks like in your posts and profile page. When I try to make signatures, it is extremely annoying because I like to be able to make my signature in the 'edit signature' page. Since I stopped using that, I would have to make the signature and preview it in an actual post or just save it to see that it looked like in one, because sometimes the post preview messes it up too. And when I get it right using that, I will preview it in the 'edit signature' page and it will look nothing like what it really does. My suggestion is that you resize the space where we see our signature when we are making it (AKA here) so that it matches the size of the space for our signature in our posts. I think that it would really help people with being able to make signatures.
Edit: have one other suggestion to add to this, I think it would be a good idea to have a character count while making your signature, much like the one when you go to edit your trading rules. I have previously put a lot of work into signatures only to see that it is way above the limit. I think it would be convenient just because it would tell you when you have reached the limit before you put a ton of time and work into it only to be disappointed by being told it has too many characters.