I tried to sort this but could not find a topic on the forums or work out in the files where the height command for the forum post Signatures are stored.
I'm using the Default theme with black/gold colour overlay.
It has signature "%" value but it does not seem to affect the height.
Here is a link to a forum with a Steam signature and it shows how the sig is cut off.
I have tested in Explorer and chrome with same cut off results.
Any advise would be appreciated.