FYI: There is a PR to enable having the rulers be different colors from each other. Looks like it is getting close. https://github.com/microsoft/vscode/pull/88453 in which colors would be set differently.
The accompanying issue: https://github.com/microsoft/vscode/issues/54312 Support multiple rulers with different colors #54312
This is now working in the Insiders' Build (it will be inFrom the February 2020 v1.43 release), you can set per-ruler colors. Use like this:
"editor.rulers": [ { "column": 80, "color": "#ff00ff" }, 100, // a ruler with the default or editorRuler.foreground color at column 100 { "column": 120, "color": "#ff0000" }, ], And seeSee the release notes here: https://github.com/microsoft/vscode-docs/blob/vnext/release-notes/v1_43.md#multiple-rulers-with-different-colors