My Power App works in Studio, but the phone layout is a mess

I start the morning feeling pretty good because the request tracker finally opens, shows the SharePoint list, and lets me submit a new item. In Power Apps Studio, the screen looks tidy enough. I send the link to two people for a quick check before the team meeting.

By mid-morning, one person sends back a phone screenshot where the buttons are half off the screen. Another says the form is usable on their laptop but awkward on a tablet. I try dragging controls around, then realise every quick fix seems to break a different screen size.

The small win is that the app still works: the data saves, the gallery loads, and the approval flow is not the issue. The painful part is that nobody judges the app by the hidden working bits. They judge it by the first broken screen they touch.

What I want is a simple way to rebuild the layout once, test it on the devices we actually use, and know what 'good enough to pilot' looks like before I send the next link.