I have been playing around the website and just noticed that when you hover over a link it turns yellow, and the connected pages appear below in a linear right-to-left line. You then have to move your mouse way over to the right to click on a page.
Instead, I think that the links should be stacked so that one just has to move the mouse down to click on the one you want. Also, the highlight colour (yellow) of the original link turns to white as the mouse moves off it to click on a corresponding page. I think that the link should stay yellow, and any page that you hover over should also turn yellow.
Does that make sense?