I'm on latest for MacOS (68.0.1) and still see the problem. Watching the rendering closely, it looks like it gets it right but then when the big Michigan image loads, that messes it up.
Two ideas:
1) Give the image a height so that Firefox knows how much space it will be using before it loads the image.
2) If that doesn't work, try applying the "local" id on something that lines up in the menu to the left (e.g., Nibbleblog, About).