Mario 3 remade with CSS animation and media queries – a remake of a demo I did a while back for a MDN Dev Derby.
Best viewed if you have your view so that the code stacks on the right, so you can expand the main window rather than your whole browser (controlled in bottom right of CodePen or at this link).
I wanted to make playing around with the demo code a little bit easier not just for myself, but for anyone interested in messing with the code.
It benefits from being inside the CodePen window, as you can just resize the inbuilt CodePen window instead of the entire browser to make the animations fire!