React, Vue, and Angular all use a virtual DOM, which means they're already deprecated 5 years from now. A virtual DOM is dumb.

SASS, SCSS, LESS, etc are kind of great though. It sucks you have to compile them to css, but you can do this:

    .App {
      .Topbar {
        .Logo { color: green }
      }
      .Content {
        h2 { color: orange; }
      }
    }

Saves a lot of time and effort.