HTML signatures distorted inside the Signatures and Stationery window preview/edit field, but display fine when used

Question

I created an HTML signature and imported it into Outlook 2010/2013 by placing the .htm file into my %APPDATA%\Microsoft\Signatures folder. The signature looks and works great, however the signature looks distorted / severely squished in width when attempting
to view the signature in the Signatures and Stationery window within Outlook. What would be causing this? Is this a common issue when using .htm signatures?
It isn't too big of an issue as the signatures do work as expected when in normal use, however some users would like to tweak theirs using Outlook's built in editor and are not currently able to.

Answer 1

In my experience at least, that's a normal behaviour. The editor isn't fully WYSIWYG so if you do anything complicated in there it won't always give an accurate representation of what will eventually be output when you insert it into a message. I've seen
the same thing with signatures copied from elsewhere, displaying fine in the email but not in the editor, so it's not restricted to imported .htm files.