Again, you seem to be misunderstanding the issue.  The logo sizing on the INVOICE is not the issue.  It is the size of the logo that appears in the EMAIL of the invoice.  These are two separate places, and I also have a logo that is supersized in the EMAIL that looks ridiculous and amateurish.  Changing the size of the logo in the custom form styles as you pointed out only changes the size of the logo on the invoice, which is NOT the problem.  Please correct this annoying and embarrassing bug.