It's blogspots "Dynamic Views". Complete dreck. I can only assume it's the default when you create a blog nowadays as I have no idea why anybody (least of all developers) would opt into that crap.
Someone at blogspot needs a smack on the head. The site takes several seconds to load, which is absolutely ludicrous for displaying plain text, and when it finally does it's unusable as you've noted.
Everything is on default from Blogspot. I only put the Gist source code displayer and the LaTeX math javascript.
If anyone is offering a new design, I would gladly take it... As long as I can concentrate on the content and not the container.