Large canvas not downsized properly when running wasm build in mobile on itch.io

I'm having trouble with the canvas overflowing when using this template targeting mobile devices and publishing on itch.io.

I'm quite sure the change in this PR https://github.com/bevyengine/bevy_github_ci_template/pull/44 previously fixed the issue and properly resized the canvas to fit smaller screens, by adding the css

```

html, body {margin:0;height:100%;}

```

and configuring the window plugin to use `fit_canvas_to_parent: true`.

But something has changed 🤔 and this does not seem to help anymore as a canvas/window with dimensions larger then the target device will overflow and only show a cropped center part of the canvas/window content, when running on mobile on itch.io.

Anyone having the same issue (with itch.io in particular) and have found a workaround / fix?

Beginne damit, den veröffentlichten WASM-Build auf einem Mobilgerät über itch.io zu reproduzieren, und vergleiche anschließend sein Canvas-Verhalten mit der Konfiguration aus PR 44. Prüfe zuerst die angezeigten CSS- und window plugin-Einstellungen; abgeschlossen bedeutet, dass das Canvas auf das Zielgerät passt, ohne Überlauf oder abgeschnittene Inhalte.

Vom Indexierungsmodell aus dem Issue-Text verfasst.