Once I learned that my code would be lost if I navigated to another lesson and back, a couple of times I wanted to open an old lesson I'd already passed through in order to refresh my memory of how to do something. Unfortunately, since the links contain no actual URL, right-clicking offered no "open in new tab" option, and Ctrl-clicking also didn't open a new tab/window. For greatest accessibility and use to those using the tutorial, and for the least amount of annoyance to more advanced users who like to work with multiple tabs, consider making the navigation work as standard links for these uses (though staying in-page without reloading when a simple click occurs). (It might also be worth considering how tabbing with the tab key and pressing Enter or Ctrl+Enter behaves.)