Thanks (creator here). Please be gentle on my server, right now it's rather overloaded ;). This particular demo is quite lightweight (2.5 MB), but some others are not.
It's all just static files, so they should load eventually, just it needs a bit of patience (I'm being pummeled right now both from here and Twitter).
If it's static files I'd recommend the cloudflare free tier to off load them on to their CDN. https://www.cloudflare.com/plans I'm not affiliated other than being a customer...