Pointer offset issue when device pixel ratio is something besides "2"

## Bevy version
main branch as of commit: https://github.com/bevyengine/bevy/commit/425570aa752b32ef26f6573b385d49d6254bd868

This is only an issue on mobile devices when the device pixel ratio is something besides 2.

I have made a minimum viable example using one of the bevy web examples and modifying it to use the new css full screen method.

https://github.com/miketwenty1/bevy_broken_on_mobile

I'll include a video here to demo the offset issue:

https://github.com/bevyengine/bevy/assets/7761473/68c20890-e79e-4839-b455-5625596c04de

Here you can see when Pixel 7 is used with a device pixel ratio of 2.65 it has an offset from where the press is and where it corresponds. When an iPhone SE is used with a device pixel ratio of 2, it works. I assume there may be desktop devices with pixel ratios other than 2? So this may effect more than just mobile devices.

may be related to https://github.com/bevyengine/bevy/issues/11052