Dark/light mode

[l3aj1]

Hello,
I have a school project to make a website using only html, no css or javascript or anything else. I have a problem with making dark/light mode using only html, i managed to do it using css but like I said we cant use it. Is it even possible to do it without css? We dont need to do it but I want my page to have it.
Thanks!

 

[Lucas]

I only make use of XenForo forum software for setting up my forum. It's very easy using either light theme or dark theme when compared to how different it is with using CSS or HTML.