I have a Parent.js component with a child component Child.js inside of it.
Parent.js imports parents.css
Child.js imports child.css
If I define this in child.css:
.example {
font-family: 'Roboto', sans-serif;
}
How come I'm able to use this className in the Parent.js component as well despite not specifying it in the parent.css?
Unless you use unique class names, CSS Modules or some other alternatives available for scoping CSS styles to any component in React, styles specified in any CSS file will be applied globally.
If you want to limit styles to any component, use CSS Modules or make sure every class name is unique in your project.
For details on how to use CSS Modules, see Adding a CSS Modules Stylesheet. You can also look at 9 Ways To Implement CSS in React JS for other available alternatives.
I recommend using unique class names. For example, lets say you have multiple ListView components: MemberUsersListView, AdminUsersListView, TestUsersListView; and each of them needs to be styled differently. I would create the following CSS classes:
.MUListView{
...
}
.AUListView{
...
}
.TUListView{
...
}
I know this seem's annoying, but it's cleaner than applying inline styles and easier to implement on smaller projects.
Related
I'm relatively new to Angular, and I have a doubt about component stylesheets.
I have an Angular 12 app and created a component named my-component. The template of the component in question is something like this:
my-component.html
<div>
...some html...
<some-other-angular-component></some-other-angular-component>
...some other html...
</div>
some-other-angular-component is another component, either from the app itself or a third party library.
Now, what I want to do in my-component is apply some CSS rules to the contents of some-other-angular-component. I know that the HTML it generates contains classes that I can target, so I tried to add this to my component CSS:
my-component.scss
.some-other-angular-component-inner-class {
background-color: red;
}
However, this doesn't work, it appears that the component's CSS file only applies rules to the HTML defined directly in the component's template, not the HTML generated by sub-components.
Is there a way to make this work? I find myself having to add my CSS to the webapp's main style.scss file, even when I want to apply the rule only to the particular some-other-angular-component instance inside of my-component. It makes styling confusing and needlessly fragmented. Is this intended, or what am I missing?
I think you may want to look into View Encapsulation.
#Component({
selector: 'app-no-encapsulation',
template: `
<h2>None</h2>
<div class="none-message">No encapsulation</div>
`,
styles: ['h2, .none-message { color: red; }'],
encapsulation: ViewEncapsulation.None,
})
export class NoEncapsulationComponent { }
These styles will be added to head and will be applicable to other components as well if style rule matches.
Please note, with this you are only enabling this behaviour for just this component. Chances of overlapping CSS rules is still there but is lot less in comparison to directly putting styles in style.css.
I will also suggest that you add .class or #id attribute in mark up to ensure that your rules don't overlap by default.
For example:
.my-component .rule-one {
}
It will ensure that my rules are only applied are on component that has this class applied on it.
I have two components with tab groups in them. One is a main page and I have overwritten the css to make the labels larger, done using ViewEncapsulation.None. The other is a dialog, and I want to keep it small but still apply some other custom styles to it.
When I open the dialog after visiting the other tabs page, it copies all the styles, which I have figured is because ViewEncapsulation.None bleeds CSS but not exactly as expected.
Is there anyway to override Angular Material styles without changing ViewEncapsulation so that I can keep the two components separate?
Solution 1: you can put all elements of your component into a parent element with a css class and override the material style into it.(it's custom capsulation)
Note: ViewEncapsulation is none here.
component.html
<div class="my-component__container">
<!-- other elements(material) are here -->
</div>
component.scss
.my-component__container{
// override material styles here
.mat-form-field{...}
}
Solution 2: use /deep/(deprecated).(use ::ng-depp insteaded)
:host /deep/ .mat-form-field {
text-align: left !important;
}
Solution 3: don't change ViewEncapsulation , then:
:host {
.my-component__container{}
}
if you would like to customise your Angular material components and provide your own stylings, I have the following suggestions. You may use one of them.
1) Overwrite the classes on your main style.css (or style.scss, whichever you are using). If you are wondering, it is the one that is on the same directory level as your index.html, main.ts, package.json, etc. You might need to add the !important declaration.
For instance,
.mat-form-field-label {
color:blue!important;
}
2) Customising the various Angular Material directive (such as MatPlaceholder) by providing a custom class.
For instance, when we use the MatPlaceHolder, and on the component.html template,
<mat-placeholder class="placeholder">Search</mat-placeholder>
On your component.css, we can then supply the css properties to the placehodler class
.placeholder {
color: green
}
Note:
Alternatively you may use ::ng-deep, but I would strongly suggest using ::ng-deep as it will soon be deprecated.
::ng-deep .mat-dialog {
/* styles here */
/* try not to use ::ng-deep */
}
You can use ::ng-deep. Refer NgDeep
There's a global css class I want to override (.ant-content), but I want to do it per route, I've tried importing css files which override .ant-content per react-component that gets loaded up in various routes but they only end up loading their css even when not rendering (probably because the imports happen regardless if a component is loaded).
Assuming you have a class like this somewhere which you want to override:
.ant-content{
color: red
}
you could try using the specifity ordering rules of CSS to override this. So, for example if in one of your routes you have a component you want to overwrite which looks like this
<div className='override'>
<Component className='ant-content/>
</div>
Then in the CSS you import into that component you could use:
.override .ant-content{
color: blue
}
This should override the original .ant-content class as it is more 'specific' than the original class declaration.
You can read more about specifity here: https://www.w3schools.com/css/css_specificity.asp
I was wondering how to override the encapsulated CSS of an external component.
So I am using material2 in my project and the tabs component has a the attribute overflow set on tab-body. Is it possible to override the overflow value?
You can use the special css /deep/ instruction. See the documentation
So, if you have
app
sub-component
target-component
<div class="target-class">...</div>
You can put in your apps css (or less):
/deep/ .target-class {
width: 20px;
background: #ff0000;
}
Obviously, you can put this css fragment in sub-component as well.
From this article
Although the style of a component is well isolated, it can still be easily overridden if necessary. For that, we just need to add an attribute to the body of the page:
<body override>
<app></app>
</body>
The name of the attribute can be anything. No value is needed and the name override makes it apparent what its being used for. To override component styles, we can then do the following:
[override] hello-world h1 {
color:red;
}
Where override is the attribute, hello-world is the target component, and h1 is whatever you are trying to restyle. (get this right or it wont work).
Your component hello-world would be
selector: 'hello-world',
styles: [`
h1 {
color: blue;
}
`],
template: ` <h1>Hello world</h1> `
I think this is the most elegant way.
Alternatively if you are building a library of some sort, you can reset the styling altogether by doing something fancy in your css like:
:host-context(.custom-styles) {
//.. css here will only apply when there is a css class custom-styles in any parent elem
}
So then to use your component you'd use
<hello-world class="custom-styles">
But this is way less convenient than the first option.
::ng-deep .tag-or-css-class-you-want-to-override {
/* Add your custom css property value. */
}
The syntax ::ng-deep is used to override outside css class or tags without using ViewEncapsulation.None.
I see variations of this question a lot and since this is the top question on the subject I want to give the simplest answer. ng-deep and similar functionality is deprecated, so it's best to just rely on vanilla CSS.
Simply create a CSS selector with a higher specificity.
Most people (including myself) get hung up trying to do that because they don't understand two things:
Angular View Encapsulation
CSS Specificity
Angular View Encapsulation
View Encapsulation ensures CSS within a component only affects that component. To affect other components, you need some global CSS. You can do this by using a global style file like styles.css or by disabling View Encapsulation on a component.
#Component({
...
encapsulation: ViewEncapsulation.None
})
CSS Specificity
When two selectors select the same element, the CSS that actually gets applied is based on specificity: https://developer.mozilla.org/en-US/docs/Web/CSS/Specificity
You can increase specificity by simply adding more elements to your CSS selector. For example p.className is more specific than just .className. If you're lazy, you can just repeat a class name to increase specificity. .className.className is more specific than .className.
So to override any CSS in an Angular project, go into styles.css and repeat the class selector until your CSS has a higher specificity than the original.
.className.className.className {
color: red;
}
Didn't work? Add another .className.
Just check the class that is being applied to the tabs by the external component (use Inspector or any other tool). In your style css file, add the same name of the class for the tabs and set the overflow property along with adding !important to it to make sure it overwrites the previous one. Also make sure your css link to the page is added after the external component css link if any.
Hope this helps.
::ng-deep .css-class-you-want-to-override{
/*your custom css property value. like below */
background: white !important;
}
I am using css modules for my project, and I have a file positioning.css which has some useful classes that I want to import. e.g. .right, .left
What is the best approach for this using CSS Modules?
At the moment I can see 2 options, but they are not all that great:
composition in the component's style
.right {
composes: right from '../styles/positioning.css';
}
or
multiple css module imports in the component
import positioning from '../styles/positioning.css'
import styles from './myComponent.css';
Object.assign(styles, positioning)
class Menu extends Component {
render() {
return (
<div styleName='menu'>
<div styleName='left'>this is left</div>
<div styleName='right'>this is right</div>
</div>
);
}
};
export default CSSModules(Menu, styles);
I have manage to get this working:
// css file
#value class-to-compose from "file-where-class-is-defined.css";
.someclass {
composes: class-to-compose;
// other styles
}
One approach is to collect all app level css variables and calculations at the top level into app.css
#import "./theme/layout.css";
#import "./theme/colors.css";
...
Then reference app.css using
#import "../../app.css";
This way you can manage #import scope inside one file at the root level.
I'll go with the first proposition. (the result is quiet the same)
both proposition have quiet the same result
If someday you have to edit your Menu css, you'll just have to edit your Menu css and not your component.
You let CSSModules take decisions. (more futur proof?)
You could import the css files that you use frequently into a broader CSS file that you import on specific pages, this is taking the second approach but making it cleaner, especially if you have a lot of common core css files that you import on pretty much all pages.
I would advise you to go with [Sass] [1]. Sass allows for the usage of partials (i.e. distributed / scoped css sheets).
You write scoped (to the components you want) css and import all your partials into your main.css then.
Couple of other advantages:
you can do theming by having one partial that defines your them via variables, which you import first and then all your partials can use these variables.
having the css on a scoped level (at least to me) felt more "reactish" where components are supposed to be stand alone, but it also wasn't inline styling, which I find ugly and weird (I don't like to clutter down my .js files with styles)
[1] http://sass-lang.com/
I find this one line very helpful with importing:
#import 'file.css';
You could set these as globals and update their names to be a tad more semantic, like BootStraps pull-right.
If you declare them as
:global(.right) {
/* ... */
}
You can then just use them in your app by preferably importing globals early on in the entry point.
You should take a look at the option by vue.js component (scoped/overall)
You can choose a precompile css language like SASS, which can use #extend ...etc to reuse the common property, like below:
%common {
width: 100%;
height: inherit;
}
.my-class {
#extend %common;
}