Marquee Sandbox

I got this idea for an old site of mine, and put up a simple "Marquee Sandbox". The idea is for newbies to experiment with coding options for a simple marquee.

I put up this site a couple of years back and basically forgot all about it. Lately, I noticed that it's getting over 12,000 hits per month so decided to put up a bit of fresh content - this "sandbox" tool is such content.

Any ideas or suggestions?