If I visit a site like that, then as a Mozilla NoScript user it will initially not work – but it will with a CSS approach. I realise I am a minority in that though (probably even more so with uMatrix on Chrome). But I think it’s quite common to let CSS prevail over JS. And this is coming from someone who likes jQuery a lot.
I’d have to look into the Codepen specifics again to make sense of the third point as well…
Edit – I’m a bit clueless there to be honest.