Haha, I feel stupid now. Thanks a bunch, David!
One thing I noticed when trying to refresh the newly selected Page (well, actually the Content of it). The styles I defined in the stylesheet weren't applied anymore. They worked fine initially. I added an image and some text above the List Items, they correspond to the clicked List Item on the other Page. Here's the css (I only used the default Tersus classes):
Am I refreshing the wrong object? No other problems so far. Works pretty intuitive.
For best results, use the Firefox browser..