After switching the colors of the design, I kept the momentum and continued working on the HTML of the blog.

It took couple iterations of multiple hours, but now it's done: the HTML source of this blog is valid HTML5!

Getting rid of the obsoleteness hidden in old blogentries dating back over 20 years also led to some interesting observations.
Back when moving from HTML 4.01 to XHTML 1.1, I remember spending some time to transform old <br> tags to <br />. And now for HTML5 I did the inverse and moved all <br /> tags back to <br> :-)

Also once more I'm very thankful for the work of the Internet Archive, which helped to recover images hosted on servers long gone (like URLs which already at the end of 2002 were no longer valid!).

Overall a lot of replacing no longer existing HTML tags and attributes with CSS definitions.
And there is virtually no change to the visual representation of the blog (which was the goal), so we still have the table-based layout with pixel-sized fonts as originally drafted in 2002.
Moving this to actually leverage modern HTML5 mechanisms and making it also more mobile friendly are tasks left for some future cold winter evenings :-)