Outlook signature has wrong colors / colors change on every save of signature / signature corrupt

I created a new HTML signature in Outlook 2016 and user a user defined color by RGB values.
I the signature editor everything looked OK, but when i first used the signature in an E-Mail i recognized, that one line in the signature was black colored instead of the color i wanted.

I went back to the signature editor and saw, that the issue was still present. I colored all lines the same and saved the signature. Using it for the first time, another line was black now. Tried this a few times and the problem did not go away.

How-I-fixed-it:

Where does Outlook store the signatures? (In german: Wo speichert Outlook die Signaturen ab?)
Outlook stores the signatures in your personal data directory (this is also important to know in case you want to backup or transfer your signatures), not in any pst-file!

I went to:
C:\Users\MyUserName\AppData\Roaming\Microsoft\Signatures

There you find some file with the name of your signature, one for every E-Mail-Format.
I opened the MySignatureName.htm file and after a huge part of styles and formatting right at the end i found the HTML-Code of my signature.
I found out, that for the line(s) being black instead of my color, Outlook added the
-Tag BEFORE the text instead of after it. So the style did not affect it.I manually corrected the HTML to be the way i wanted it to be and the problem seems to be gone now.