curious, would this work in a server side rendering context?

[mreinstein]

or is this only compatible with a pure client side implementation?

[schlosser]

The issue here is that we don't know the screen size on the server, so we can't easily compute the size of the images. So probably not, unless you want to calculate a "guess" based on some hacky info like the user agent.

[mreinstein]

calculate a "guess" based on some hacky info like the user agent.

It's too bad that the Accept-CH: Viewport-Width client hint never caught on. It would have been useful for exactly this kind of scenario I think.

we don't know the screen size on the server

I'm wondering if on the server side one could set some "reasonable" initial state that assumes mobile width (e.g., 400px) and then while the page is loading, re-calculate actual viewport width. that might be ok because the server side render really just needs all the DOM elements to be generated, which gives us all the nice SEO benefits.