These are my personal test pages for HTML and CSS elements. You can have a view to the underlying code, by using your browsers inspector.
If I find some interresting web pages or demonstrations, I'm trying to rebuild it, as near to the original as possible or to crystallize out the essence of it.
Much Thanks to Steven Roberts
I modified the example, to split the inner circle into 2 parts and dislocated 2 circle centers slightly, to get a bit more of a wobbling effect. I've learned about loops in CSS.