Yeah, mobile safari is annoying in that it doesn't allow fullscreen mode for anything except video. And that it doesn't always leave you in a consistent scroll state or with knowledge of how much screen is visible. So the left/right buttons drop off the screen unless you scroll it a bit before hitting start.
Came to say the same about the original iPhone SE. I thought it was because mine is a smaller model (most sites look weird on it these days). But now I guess that's not the reason.
