Manually changing page dimensions, height disabled

Hi, why when I try to manually change dimensions of a page its height is disabled and I can only change the width? The page’s height is not set to stretch, it’s just a fixed value.

Hi @boyish_mongoose! Which element are you selecting and what do you mean by disabled? Can you send me a screenshot?

I’ve selected a mobile breakpoint page

And height is disabled, I can’t change it.