Earlier quoted context omitted.
I love the clean style of your website.
Thanks! Last time I checked my domain got penalized for having abnormal low markup or some such, which apparently makes it look like a spam site. I am proud of this.
Do you have a link to the document you were pointed to when you got penalized? If it was Google who penalized you, they must have pointed you to a URL with documentation on why you got penalized and how to resolve it.
I ask this because I run a few websites with even lesser markup than your site but I have never got penalized. I once got penalized due to excessive number of spam comments on one of my websites and they pointed me to https://support.google.com/websearch/answer/190597 ("Remove this message from your site") to resolve the issue. This issue did not affect the search ranking much though (dropped by only about 2 or 3 places in the list of results). But never had an issue with abnormally low markup.
The markup in your website looks pretty reasonable to me, so I am surprised you could get penalized for that when I have had no issues with even lesser markup and they still appear at the top of the list of results for relevant search terms.