Angular 2 / 4 CSS component A affects component B

Question

In my app I have 3 components.

AppComponente with <router-outlet></router-outlet> to route to Frontend or Backend components.

My problem is that the Frontend.component and Backend.component has diferent CSS's ... but when I RELOAD one of them, something strange happens and the CSS of the other component dont work.

I try to use encapsulation: ViewEncapsulation.None and Native/Emulated in many combinations but, the problem still happen.

Is a wrong pratice build 2 modules in one application ? Backend and Frontend ?

I'm very confuse now.