This is really great. When first learning web design I would look up CSS selectors one at a time depending on what I needed at that moment. I assume this is how

This is really great. When first learning web design I would look up CSS selectors one at a time depending on what I needed at that moment. I assume this is how most people do it because all the tutorials out there are so damn boring, and by the time you learn the fifth selector you've forgotten the first. But even now, as someone who's proficient in CSS I enjoyed completing a large chunk of this "tutorial". If I didn't already have a whole lineup of side projects I'm working on I'd try making this mobile friendly and packing it into an app. If there were more levels that got very difficult at the end it would be a fun way for people learning web design (a growing trend) to spend their time while commuting.