On CodePen, on the other hand, I focus on being creative and the end result. Not so much about the quality and structure of the code. My Pens often consist of a number of global variables and some global functions.
One of my recent Pens is different though. All strict and boring, no sound, no canvas.
Also add this as external CSS:
With CodePen's "Auto Update Preview" you can see the test results while you code. I usually turn it off though, it gets in my way.