Theme configuration

[VladislavAntonyuk]

Add light/dark theme

[StardustDL]

Thank you for advice. But I'm not familiar with CSS now. PR is welcomed if you have some ideas.
I think one workaround is using a custom markdown stylesheet, and toggling light/dark by setting the Class parameter.

[MihailsKuzmins]

a good way of implementing it is custom CSS properties which can be changed in JavaScript as it is described in this post.

Now I am not familiar with the codebase of RazorComponents.Markdown, but in the next week I could try to take a look at this (I need to toggle dark/light themes for markdown)