Make Nextcloud ignore OS dark mode

Hi there. I just installed Nextcloud and I really like it, the only problem is that I can’t make it ignore the OS dark mode. Whatever I share to a client it adapts to the OS dark mode (if it is on, and it mostly is) and the buttons are barely readable and also dark mode is not suitable with my company branding, It needs to be all white with blue logo, not black. Is there any way to fix this?

Thank you!

what operating system are you talking of? Which client? Which server version?

For users without a login Nextcloud 20 asks the browser if the user prefers dark mode: There is no way to turn it off.

The version is 20.0.3, and the problem comes with MacOS and iOS that have the dark mode enabled.
If it is like kesselb say that it cannot be turned off, it’s really bizzare.