Digital Clock
For me the main challenge for this clock was to make it scalable, so I created leds that were measured in units and then put a global multiplier on them. If you change the multiplier, all the units change equally so all the proportions stay the same.
By the way if you were to change the viewport of this page, you will see the clock scale along with the page, but that is just the css scaling the canvas (using a clamp command).