Do you mean the regexp in https://github.com/karlb/karl.berlin/blob/master/blog.sh#L4 ? It doesn't remove the formatting, just HTML comments (because they would show up on the page, otherwise) and rel="me" attributes (because they don't work with md2gemini). Feel free to read the blog post about adding Gemini support for more details: https://www.karl.berlin/gemini-blog.html