[ExactActuation]

WTF? Mind blown. And I've been hacking the web for nearly 20 years now.

[Zetaphor]

It's amazing how well the effect works. Here's a demo:

https://jsbin.com/kuzolurapi/1/edit?html,output

[scatters]

In Chrome, the outer marquee needs (CSS to) be forced to full height. https://jsbin.com/rasivitupi/edit?html,output

[gpvos]

Same in Firefox.

[saagarjha]

That doesn't work in my browser :(

[sedatk]

it only moves horizontally on iOS.

[swyx]

desktop chrome too