bug? fullscreen mode for an entire html page or a text element

I'm working on implementing fullscreen mode in my application.

Fullscreen functionality is commonly used for HTML video or img tag elements.
In those scenarios, it behaves as expected.

However, when fullscreen is triggered for a text element, the colors appear incorrectly.
As soon as the element enters fullscreen, the background turns black and the text color is wrong.

Is it valid to apply fullscreen mode to text elements, or is this considered non-standard usage?

The same issue occurs when fullscreen is requested for the entire HTML page.

You can easily reproduce this by running the following script in the browser console:

document.body.requestFullscreen();

(page "edge://system/" is good for this test)
After activation, the text background becomes black and the text color is wrong.

I understand a black background could be good for image or video to fill unused space,
but not for text elements.

The background is always black even with PreferredColorScheme dark or not.

Start by reproducing the behavior in edge://system/ with document.body.requestFullscreen(), then compare fullscreen on the text element and the entire page, including the preferred color scheme. There are no repository files or tests named; done would be a clear determination of whether the color and background behavior is a bug or expected fullscreen rendering, with the relevant limitation documented.