They’re likely using react native (Microsoft has pretty much gone all in on react for new ui things). It’s not as crazy as it sounds, the majority of cross platform mobile apps use react native.

It’s important to note that it’s not a web browser that’s rendering the ui. The way it works is that react native provides a way for js logic to define the ui declaratively (kinda like HTML), then react native calls platform native components to do the actual rendering. So you declare <Button> and what comes out on the other end is a real, genuine windows-provided button.

You can’t switch banks?

I apparently got blocked by their anti bot system on mobile

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