Vojtěch Káně
058de79991
It defaults to 100vw, which may be wasteful sometimes, but it guarantees smooth experience. I am not aware of any simple way of requesting the current widescreen behavior "make it as wide as possible while not exceeding 30rem height" using the sizes attribute. This setting may be especially wasteful for portrait images, as their rendered width will be much smaller than the viewport width.
Pátek.cz
Source code for the official Pátek website.