Problem with auto-email

I have an email that goes out automatically to anyone that fills out their name and email on my site. For some reason, the font size I set on the auto-email does not match what actually goes out. For example, I have the font size set at 12, but when it gets sent, it's actually size 16.

Also, the email seems to have a faint color background, but the text has a white background. This creates a weird look.

Any ideas?

I am not sure where you get this bigger font, I just sent a test submissions and was able to get the email with the right font size