React can easily incorporate CSS from multiple components

Question

React can easily incorporate CSS from multiple components

I'm experiencing a CSS import issue in my React project. I have a "Home" page that imports Home.css and a "Hero" page that imports Hero.css. Strangely, the styles from Hero.css are being applied to every page in the application without me explicitly declaring it. How can I resolve this issue? Here are the components involved:

App:

import './App.css';
import { BrowserRouter as Router, Route, Routes } from "react-router-dom";
import Home from './pages/home/Home';
import Hero from './pages/hero/Hero';

function App() {
  return (
    <Router>
      <Routes>
        <Route path="/" element={<Home />}></Route>
        <Route path="/hero" element={<Hero />} ></Route>
      </Routes>
    </Router>
  );
}

export default App;

Hero:

import './Hero.css';

function Hero() {
    return <div>
        <h1>Hero!</h1>
        <button className='glow-on-hover' disabled>test 1</button>
        <button className='small-button glow-on-hover'>test 2</button>
        <button className='small-button glow-on-hover'>test 3</button>
    </div>;
}

export default Hero;

Hero.css:

div {
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    justify-items: center;
    background-color: #002bff;
}

Home:

import './Home.css';

function Home() {
    return <div>
        <p>Home!</p>
    </div>;
}

export default Home;

Even though the Home.module.css file is empty, the div in the Home component is blue which is only declared in the Hero.module.css. How can I correct this?

html css reactjs

Answer 1

Answer №1

It's crucial to recognize that including CSS in a JavaScript page is not a built-in feature of JavaScript itself; it instructs bundlers like Webpack to add the CSS during the build process.

Furthermore, CSS doesn't have inherent methods for limiting its effects to specific components. It's up to you to apply scoping through classes or other means.

For instance:

React

return <div className="component-hero">
  ...

CSS

.component-hero {
  ...
}

Edit:

Although the information above reflects the nature of CSS, there are tools available that can automate scoping with unique identifiers. Refer to other answers for more details.

Answer 2

It's crucial to recognize that including CSS in a JavaScript page is not a built-in feature of JavaScript itself; it instructs bundlers like Webpack to add the CSS during the build process.

Furthermore, CSS doesn't have inherent methods for limiting its effects to specific components. It's up to you to apply scoping through classes or other means.

For instance:

React

return <div className="component-hero">
  ...

CSS

.component-hero {
  ...
}

Edit:

Although the information above reflects the nature of CSS, there are tools available that can automate scoping with unique identifiers. Refer to other answers for more details.

Answer 3

Answer №2

Due to the lack of a built-in scoping mechanism in CSS Rules for specific components, this behavior is considered normal. As a result, all div elements within the component tree will be affected by this import.

To address this issue, I suggest using CSS Classes to create a layer of scope that is at least semantically meaningful.

<div className="hero-container">
  // nested jsx...
</div>

You can then define CSS rules in your hero.css file:

.hero-container {
  // css-rules
}

If you are using the create-react-app toolchain, there is a feature called CSS Modules. For more information on CSS Modules, refer to the official documentation here.

Since all CSS is bundled into a single index.css file in the end, maintaining distinct class names can become challenging in larger projects. Therefore, it is advisable to consider using solutions like CSS Modules or third-party libraries such as styled-components, which style our components in a more tightly coupled manner.

Answer 4

Due to the lack of a built-in scoping mechanism in CSS Rules for specific components, this behavior is considered normal. As a result, all div elements within the component tree will be affected by this import.

To address this issue, I suggest using CSS Classes to create a layer of scope that is at least semantically meaningful.

<div className="hero-container">
  // nested jsx...
</div>

You can then define CSS rules in your hero.css file:

.hero-container {
  // css-rules
}

If you are using the create-react-app toolchain, there is a feature called CSS Modules. For more information on CSS Modules, refer to the official documentation here.

Since all CSS is bundled into a single index.css file in the end, maintaining distinct class names can become challenging in larger projects. Therefore, it is advisable to consider using solutions like CSS Modules or third-party libraries such as styled-components, which style our components in a more tightly coupled manner.

Answer 5

Answer №3

When you import CSS globally using import './Home.css';, it applies the styles globally. If you want to apply CSS styles locally to a component, there are different options available.

Option 1: You can use module.css files where all class names and animation names are scoped locally by default. This means you can declare styles using classes but not IDs. Here's an example:

.home {
  background: green;
}

You can then import this into your JSX file and apply the class like this:

 import homeStyles from './home.module.css';
 
 export const Home = () => {
   return (
     <section className={homeStyles.home}>
       Example of module.css
     </section>
   );
 };

In this code snippet, homeStyles is an object that contains the home class property for styling the section element.

Option 2: Another option is to use Styled Components, which is a third-party library with extensive resources for styling components. Material-UI V5 also uses this styling pattern. Here's an example:

import styled from "styled-components";

const SectionWrapper = styled.div`
  .home {
    background: green;

    @media screen and (max-width: 600px) {
      background: red;
    }
  }
`;

export const Home = () => {
  return (
    <SectionWrapper>
      <div className="home">Example of styled-component</div>
    </SectionWrapper>
  );
};

In styled components, you can also use media queries like in module.css. The example above shows how the background color changes to red when the screen size is less than 600px. For more information, visit the official site.

Answer 6

When you import CSS globally using import './Home.css';, it applies the styles globally. If you want to apply CSS styles locally to a component, there are different options available.

Option 1: You can use module.css files where all class names and animation names are scoped locally by default. This means you can declare styles using classes but not IDs. Here's an example:

.home {
  background: green;
}

You can then import this into your JSX file and apply the class like this:

 import homeStyles from './home.module.css';
 
 export const Home = () => {
   return (
     <section className={homeStyles.home}>
       Example of module.css
     </section>
   );
 };

In this code snippet, homeStyles is an object that contains the home class property for styling the section element.

Option 2: Another option is to use Styled Components, which is a third-party library with extensive resources for styling components. Material-UI V5 also uses this styling pattern. Here's an example:

import styled from "styled-components";

const SectionWrapper = styled.div`
  .home {
    background: green;

    @media screen and (max-width: 600px) {
      background: red;
    }
  }
`;

export const Home = () => {
  return (
    <SectionWrapper>
      <div className="home">Example of styled-component</div>
    </SectionWrapper>
  );
};

In styled components, you can also use media queries like in module.css. The example above shows how the background color changes to red when the screen size is less than 600px. For more information, visit the official site.

React can easily incorporate CSS from multiple components

Answer №1

React

CSS

Edit:

Answer №2

Answer №3

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