Load Different CSS Rule Depending on The Browser in an Angular 4 Component

Load external CSS into component

See also https://angular.io/docs/ts/latest/guide/component-styles.html

View encapsulation

To allow external styles to affect the content of components you can change view encapsulation (that's what prevents styles to "bleed into" components).

@Component({
    selector: 'some-component',
    template: '<div></div>',
    styleUrls: [
        'http://example.com/external.css',
        'app/local.css'
    ], 
    encapsulation: ViewEncapsulation.None, 
})
export class SomeComponent {}

View encapsulation fulfills a purpose. The better way is to add styles directly to the component they should affect.
ViewEncapsulation is set per component and may come handy in some situations.

"shadow piercing"

You can also use shadow piercing CSS combinator ::ng-deep (>>> and /deep/ are deprecated) to build selectors that cross component boundaries like

:host ::ng-deep .ng-invalid {
  border-bottom: solid 3px red;
}

• update
  ::slotted is now supported by all new browsers and can be used with `ViewEncapsulation.ShadowDom
  
  https://developer.mozilla.org/en-US/docs/Web/CSS/::slotted

which styles all tags with a class ng-invalid in the current component or any descendant with a red underline no matter if encapsulation is None or Emulated. It depends on browser support whether /deep/ works with Native (as far as I know this is not supported by any browser anymore).

Note

The shadow piercing CSS combinators are similar to the ones from the shadow DOM spec where they are deprecated since quite a while.

With the default ViewEncapsulation.Emulated Angulars own /deep/ and ::shadow implementation are used and they will work even when Chrome removes native support.

With ViewEncapsulation.Native Angular uses Chromes shadow DOM CSS combinators (only Chrome supported them at all anyway AFAIK). If Chrome finally removes them, then they won't work in Angular as well (again ViewEncapsulation.Native only).

Global styles

Styles added globally (index.html) don't consider component boundaries. Such styles are not rewritten by Angular2 and ViewEncapsulation.Emulated doesn't apply to them. Only if ViewEncapsulation.Native is set and the browser has native shadow DOM support, then global styles can't bleed in.

See also this related issue https://github.com/angular/angular/issues/5390

How to set different css class based on screen size in Angular?

You can add hostlistener to your component.

public size700_1020 = false;
public size400_700 = false;

@HostListener('window:resize', ['$event'])
onResize(event) {
   alert(window.screen.availWidth);
   alert(window.screen.availHeight);

   if(window.innerWidth < 700 && window.innerHeight < 1020) {
       // now based on the screen size you want to check 
       // enable the variable and make it true
       // based on it, you can enable the class in template
   } 
}

In template:

<div class="size700_1020 ? 'addThisClass' : 'elseThis'"></div>

There are multiple properties for your requirement on window object. I am attaching some links which might give you more ways here1 and here2.

You can also do this.

import { Platform } from 'ionic-angular';

...
private width:number;
private height:number;

constructor(private platform: Platform){
    platform.ready().then(() => {
        this.width = platform.width();
        this.height = platform.height();
    });
}

As per the changes made in the question:

  <button [ngClass]="miniClass ? 'addMiniClass':'extendedClass'" class="mdc-fab mdc-fab--touch    ">
<div class="mdc-fab__ripple"></div>
<span class="material-icons mdc-fab__icon">mail</span>
<!-- <span class="floating-span">My Invite Link</span> -->
<div class="mdc-fab__touch"></div>

How to adjust import order of .css files in Angular

You need to change to,

"styles": [
    "styles.css" 
],

Then,
Link all CSS files in styles.css.
Include all files at the top of the styles.css file.

@import url('~bootstrap/dist/css/bootstrap.min.css');
@import url('deeppurple-amber.css');
@import url('~@angular/material/prebuilt-themes/deeppurple-amber.css');
@import url('another_css_file_from_angular_material.css');
@import url('app.component.css'); 
@import url('current-vehicle.component.css');

I hope this will work.

Apply different css stylesheet for different parts of the same web page

You can't apply different stylesheets to different parts of a page. You have a few options:

The best is to wrap the different parts of the page in divs with class names:

<div class='part1'>
    ....
</div>

<div class='part2'>
    ....
</div>

Then in your part1 CSS, prefix every CSS rule with ".part1 " and in your part2 CSS, prefix every CSS rule with ".part2 ". Note that by using classes, you can use a number of different "part1" or "part2" divs, to flexibly delimit which parts of the page are affected by which CSS rules.

Style.css of Angular not applying to certain Component

Try to remove styles from the your.component.css which overlapps in styles declared in styles.css and all global styles should be applied.
Or you override your styles in styles.css by declaring new classes which are placed lower than your desired styles.

Some your global styles are not applied because of CSS specifity rule.
Read a great article at mdn about CSS speicifity.

Try to avoid using !important keyword by using CSS specifity rules. It's almost never a good idea to use !important.

UPDATE:

Chrome Developer tools shows that CSS properties 'trans-msg-his-dialog' are overridden. It can be seen by struck-through lines at CSS properties.

1. You can see which properties won by clicking Computed style tab:
   

2. Or try to move these styles to the bottom of style.css file:

   .content-body a {
       cursor: pointer;
       text-decoration: none;
       color:  #4c90c7
   }
   
   .content-body a:hover {
       color: #346092;
   }
   
   .content-body a:visited {
       text-decoration: none;
       color: #4c90c7
   }
   

UPDATE 1:

Now we know that Bootstrap style has too strong selectors and overrides your anchor:

a:not([href]):not([tabindex]) {
    color: inherit;
    text-decoration: none;
}

We see that if <a> tag does not have href or tabindex attributes, then it will have color: inherit and text-decoration: none;. So try to add href attribute to your anchor tag:

<a href="javascript:;">Button</a>

How to style child components from parent component's CSS file?

Update - Newest Way

Don't do it, if you can avoid it. As Devon Sans points out in the comments: This feature will most likely be deprecated.

Last Update

From Angular 4.3.0 till even now (Angular 12.x), all piercing css combinators were deprecated. Angular team introduced a new combinator ::ng-deep as shown below,

DEMO : https://plnkr.co/edit/RBJIszu14o4svHLQt563?p=preview

styles: [
    `
     :host { color: red; }
     
     :host ::ng-deep parent {
       color:blue;
     }
     :host ::ng-deep child{
       color:orange;
     }
     :host ::ng-deep child.class1 {
       color:yellow;
     }
     :host ::ng-deep child.class2{
       color:pink;
     }
    `
],

template: `
      Angular2                                //red
      <parent>                                //blue
          <child></child>                     //orange
          <child class="class1"></child>      //yellow
          <child class="class2"></child>      //pink
      </parent>      
    `

---

Old way

You can use encapsulation mode and/or piercing CSS combinators >>>, /deep/ and ::shadow

working example : http://plnkr.co/edit/1RBDGQ?p=preview

styles: [
    `
     :host { color: red; }
     :host >>> parent {
       color:blue;
     }
     :host >>> child{
       color:orange;
     }
     :host >>> child.class1 {
       color:yellow;
     }
     :host >>> child.class2{
       color:pink;
     }
    `
    ],

template: `
  Angular2                                //red
  <parent>                                //blue
      <child></child>                     //orange
      <child class="class1"></child>      //yellow
      <child class="class2"></child>      //pink
  </parent>      
`

---

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