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.
It's a sadly commonly used theme that also does not display anything at all if you don't enable Javascript.
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Requiring tons of javascript and seconds of load time to display plaintext? Yeah, that is pretty crazy.
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.