> For my web sites I don‘t decide on color styles. It‘s all system style.

This is false, I had a look, if you are talking about the sites you linked in your Keybase profile, I found that you are using prefers-color-scheme to decide what colors the visitor should see if they have dark mode. This is exactly I'm asking others to implement.

    @media(prefers-color-scheme:dark) {
      body {
        color:#fff;
        background:#000
      }
      a:link {
        color:#cdf
      }
      a:hover,
      a:visited:hover {
        color:#def
      }
      a:visited {
        color:#dcf
      }
    }

If you didn't know that you had this, then you might be using a CSS framework without actually understanding what it does.

No further comments by me will be added here.