BBBModal background does not follow the BBB client dark mode

[Arthurk12]

Describe the bug
When dark mode is enabled in the BigBlueButton client, BBBModal does not get the dark background that BBB uses for its own modals and menus. It either keeps a white background or, at best, gets darkreader's generic inversion, with a color that doesn't match the rest of the client.

The modal background comes from the colorWhite token (--color-neutral-white). The BBB client doesn't map that token in its dark theme. It maps --color-white instead.

The background is set as an inline style, so consumers can't override it with a regular CSS rule and have to fall back to !important on the modal's id.

To Reproduce
Steps to reproduce the behavior:

1. Render a BBBModal inside a BBB plugin.
2. Enable dark mode in the client settings.
3. Open the modal: its background doesn't match the client's dark modals.

Expected behavior
The modal background follows the client dark theme, just like BBB's native modals.

Additional context
The same token is used by the sticky footer (stickyFooter), which has the same issue.