Not a big deal - curious, HTMLBody font determination

[sxschech]

I found code that creates email message. When I see the results in outlook, I noticed that the Font and Point size for the first line is Times 12 pt, while subsequent lines are Calibri 11. If I manually open outlook and click New Message, and paste stbody, it renders all in Calibri 11. I haven't deliberately formatted fonts or sizes and the text is all one string, is there another setting that is telling outlook to render line 1 ("Hello ...") in a different font than all the other lines? It's not a big deal so I understand if there are no responses to this post.

Partial code:

...
...
stBody = "Hello " & rs!FirstName & ",<br><br>" & _
                 "Thank you again teaching today. Attached are the " & _
                 "evaluation responses from your most recent courses. <br><br>" & _
                 "If you have any questions, please let me know.<br><br> " & _
                 "Thank you,<br>"
...
...
With MailOutLook
          .BodyFormat = 3      'Late binding in lieu of olFormatRichText
          .To = rs!PrimaryEmail 
          '.cc = ""
          '.bcc = ""
          .Subject = "Evaluation Results"
          .HTMLBody = stBody & "<br>" & Signature
...
...