Style html,body from web component (Angular 2)

You need to change the way your component serves css using ViewEncapsulation. By default it's set to Emulated and angular will

add an attribute containing surrogate id and pre-process the style rules

To change this behavior import ViewEncapsulation from 'angular2/core' and use it in component's metadata:

@Component({
  ...
  encapsulation: ViewEncapsulation.None,
  ...
})

I'm not sure if this is exactly what you're looking for but this won't leave you with a permanently changed body background-image.

Here is how I did it for something similar. If tou want to impact the body background image for just this page this may work. (I've not tested this fully but it seems to work on windows browsers.)

Inside your component you can just work directly through the DOM when the component gets constructed. When it gets destroyed you can undo the change.

export class SpecialBackground  {
  constructor(){
    document.body.style.backgroundImage = "url('path/to/your/image.jpg')";
    document.body.style.backgroundPosition = "center center";
    document.body.style.backgroundRepeat = "no-repeat";
    document.body.style.backgroundAttachment = "fixed";
    document.body.style.backgroundSize = "cover";
  }
  ngOnDestroy(){
    document.body.style.backgroundImage = "none";
  }
}

For your purposes you can use a different function (rather than the constructor) when you button is clicked and you should good to go.

The way I used it is

constructor() {
    document.body.className = "bg-gradient";
  }

ngOnDestroy(){
    document.body.className="";
  }

This will dynamically add and remove style from the body for a particular component.

You could try

body {
  /* body styles here */
}

but styles in components are not supposed to be applied to elements outside themselves.

Another way is to use body as selector in your main component and use host-binding to set/remove a CSS class on body to make CSS you added to your index.html match.

@Component({
  selector: "body", 
  host: {
    "[class.some-class]":"someClass" 
  }, 
}) 
export class AppComponent {
  constructor(private loginService: LoginService) {
    loginService.isLoggedInChanged.subscribe((value) => {
      this.someClass = value;
    });
  }
  someClass: bool = false;
}

when you set someclass to true (usind some binding to a service, the class gets added to the body.

If you don't want to add CSS globally you can also bind to a style attribute directly

@Component({
  selector: "body", 
  host: {
    "[style.background-image]":"bodyBackgroundImage()" 
  }, 
}) 
export class AppComponent {
  bool isLoggedIn = false;
  constructor(private loginService: LoginService) {
    loginService.isLoggedInChanged.subscribe((value) => {
      this.isLoggedIn = value;
    });
  }
  function bodyBackgroundImage() {
    return this.isLoggedIn ? 'url("gradient_bg.png")': 'none';
  }
}

update

DomAdapter is gone. Renderer2 should provide similar functionality.

A way to style <body> directly from the login component is to use the DomAdapter (see also https://github.com/angular/angular/issues/4942)

System.import('angular2/src/platform/browser/browser_adapter').then(function(browser_adapter) {
  browser_adapter.BrowserDomAdapter.makeCurrent();
})
...
_dom: DomAdapter = new BrowserDomAdapter();
_dom.setStyle(_dom.query('body'), 'padding', '50px');

I just edited the styles.scss file and it worked for me.

Style html,body from web component (Angular 2)

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