Each Angular 2 Component can have its own styles which will remained contained inside the component. These isolated styles allow you to add whichever styles you want without worrying about them leaking out and affecting the rest of your application.
import {Component, Input} from "@angular/core";
@Component({
selector: ‘widget-one‘,
styles:[`
:host{
display: block;
border: 3px dashed black;
font-family: "Times New Roman";
}
`],
template: `
<h2>One‘s message:</h2>
<h3>{{message}}</h3>
`
})
export class WidgetOne{
@Input() message;
}
Notice three things:
1. If you want to apply style to ‘widget-one‘ tag, which means the host element for the component, you need to use ‘:host‘.
2. The style apply only has affect to this component, won‘t have any effect to other component.
3. The host component doesn‘t have any ‘display‘ attr setup, so you need to set it as ‘flexbox‘ or ‘block‘, or any other display prop....
[Angular 2] Style Angular 2 Components
原文：http://www.cnblogs.com/Answer1215/p/5891257.html