“More” seperator not visible in visual mode

First of all: very nice plugin! Thanks! It made my life a lot easier.

I have a small issue though. After I setup everything, I noticed that, when typing an article in the visual editor, the “More” seperator in the Classic-editor is not visible anymore. It is in the code (Text) editor. So, the button works, but it just doesn’t show.

Also, the font changed to Verdana. I’m not sure what it was before, but it’s different now.

When I disable the plugin, everything is back to normal.

I hope someone can help me out.

The page I need help with: [log in to see the link]