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DonkeyBanana
DonkeyBanana

Reputation: 3556

Angular: Component styles do not cascade to sub-components?

In my app.component.html I have the following, working class assignment.

<body>
  <span class="test">SHABOO</span>
  <div class="container">
    <router-outlet></router-outlet>
  </div>
</body>

In the outlet, a component is rendered and it contains the following.

<span class="test">HAZAA</span>

I expected it to get the same style as the first one but it seems that the style doesn't cascade down to the component. It made me uncertain if I'm mistaken about how the styles are supposed to behave between parent and child components in Angular.

I made sure that the name of the class isn't overriden (to exclude the risk of collision). At the moment, I'm putting similar chunks of SCSS code in each component and that's obviously bad practice.

If I @import "../app.component.scss", the styles kicks in. But I was under the impression that even without the import, the style is supposed to cascade.

Upvotes: 4

Views: 5505

Answers (5)

Christopher Peisert
Christopher Peisert

Reputation: 24134

Angular components use view encapsulation. This is by design so that components are reusable across applications. To treat a component's styles as global, set the view encapsulation mode to none (not recommended).

Instead of using none, register global style files in the Angular CLI styles section, which is pre-configured with the styles.css file.

Component CSS styles are encapsulated into the component's view and don't affect the rest of the application.

To control how this encapsulation happens on a per component basis, you can set the view encapsulation mode in the component metadata. Choose from the following modes:

  • ShadowDom view encapsulation uses the browser's native shadow DOM implementation (see Shadow DOM on the MDN site) to attach a shadow DOM to the component's host element, and then puts the component view inside that shadow DOM. The component's styles are included within the shadow DOM.

  • Native view encapsulation uses a now deprecated version of the browser's native shadow DOM implementation - learn about the changes.

  • Emulated view encapsulation (the default) emulates the behavior of shadow DOM by preprocessing (and renaming) the CSS code to effectively scope the CSS to the component's view. For details, see Appendix 1.

  • None means that Angular does no view encapsulation. Angular adds the CSS to the global styles. The scoping rules, isolations, and protections discussed earlier don't apply. This is essentially the same as pasting the component's styles into the HTML.

To set the components encapsulation mode, use the encapsulation property in the component metadata:

src/app/quest-summary.component.ts

// warning: few browsers support shadow DOM encapsulation at this time
encapsulation: ViewEncapsulation.Native

ShadowDom view encapsulation only works on browsers that have native support for shadow DOM (see Shadow DOM v1 on the Can I use site). The support is still limited, which is why Emulated view encapsulation is the default mode and recommended in most cases.

External and global style files

When building with the CLI, you must configure the angular.json to include all external assets, including external style files.

Register global style files in the styles section which, by default, is pre-configured with the global styles.css file.

See the CLI wiki to learn more.

Upvotes: 4

dota2pro
dota2pro

Reputation: 7856

If you want a global style put it in the global file styles.css or styles.[Your css preprocessor]

See this example https://stackblitz.com/edit/angular-a5ntm6?file=src%2Fstyles.css

I put test class at the end

.test{
  color:red;
}

Upvotes: 0

Md Rafee
Md Rafee

Reputation: 5530

This is how angular works. Every component is separated with it's CSS, even if it is child component of a parent. They can't inherit their parent CSS.

Haza span component is child of your app component, but it is separated component. So, you can't get those Shaboo styling to Haza.

Solution:

if you want to maintain same CSS, there are multiple ways.

  1. Recommended way:

    a) if it is only for onle class, copy the class to the child component.

    b) if it is for huge number of classes, create a css file for them and import them in both parent and child component css. Example:

    @import '../span.css';

  2. you can add this css to styles.css. then you will get it anywhere in the app. if you want this style many places, you can do it.

  3. As @Christopher Peisert mentioned, by using

    encapsulation: ViewEncapsulation.Native end of the @component decorator in child.component.ts. It is not recommended way

Upvotes: 4

Kousika Ganesan
Kousika Ganesan

Reputation: 609

It works like that. If you are in need of having a common style then add it in the global styles.scss file.

Upvotes: 0

jamesbcn
jamesbcn

Reputation: 347

The global CSS files are those that are listed in angular.json. All others CSS files are encapsulated by default (this can be removed but is not recommended.)

Keeping your global CSS organised is important as your application grows. What I like to do is create a global styles folder and then add new files for different widgets that I might be altering. Since removal of ::ng-deep these types of changes have to be done in the global scope.

Upvotes: 0

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