[Vuejs]-.router-link-active not working in vue css

Scoped attribute makes the styles to be constrained. Styles are applied only to your component, it do not leak into children components.

Basically, scoped makes it (nomen omen) SS instead of CSS. Just StyleSheets, without Cascading.

You can either remove scoped from your style declaration or define some general top level styles for (lets say) all of active router links for the whole app.