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; }
}
}