That's what I love about iPhone13 mini with Safari. You spot badly designed sites immediately.
(This site's buttons are too wide and it bumps from left to right when scrolling sideways.)
It's still a free CSS kit, but now I know there's no care behind it.
I remember how IE5 used to be the bottom rung to test a design against.
(The site renders perfectly for me in Firefox on Linux. I never owned an iPhone. I suppose whatever AI model was working on it also used a single desktop browser.)