Global Styles in Next.js: Applying Styles Across Your Application

Global styles are a crucial part of any web application, allowing you to define styles that apply across the entire application. In Next.js, you can apply global styles using CSS files, CSS Modules, or Styled-jsx. In this article, we’ll explore how to use global styles in Next.js, including best practices and common techniques.

What are Global Styles?

Global styles are styles that apply to the entire application, rather than being scoped to individual components. They are typically used for defining base styles, such as typography, colors, and layout, that are shared across multiple components.

Using Global Styles in Next.js

In Next.js, there are several ways to apply global styles:

1. Using a Global CSS File

You can create a global CSS file and import it into your application. To do this, create a CSS file in the styles directory and import it in the _app.js file.

/* styles/globals.css */
body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  background-color: #f4f4f4;
}

// pages/_app.js
import '../styles/globals.css';

export default function MyApp({ Component, pageProps }) {
  return <Component {...pageProps} />;
}

In this example, the global styles defined in globals.css are applied to the entire application.

2. Using CSS Modules

You can also use CSS Modules to define global styles by using the :global selector. Here’s an example:

/* styles/globals.module.css */
:global(body) {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  background-color: #f4f4f4;
}

// pages/_app.js
import styles from '../styles/globals.module.css';

export default function MyApp({ Component, pageProps }) {
  return <Component {...pageProps} />;
}

In this example, the global styles are defined using the :global selector in a CSS Module.

3. Using Styled-jsx

You can use Styled-jsx to define global styles by using the <style jsx global> tag. Here’s an example:

// pages/_app.js
export default function MyApp({ Component, pageProps }) {
  return (
    <>
      <Component {...pageProps} />
      <style jsx global>{`
        body {
          font-family: Arial, sans-serif;
          margin: 0;
          padding: 0;
          background-color: #f4f4f4;
        }
      `}</style>
    </>
  );
}

In this example, the global styles are defined using the <style jsx global> tag in the _app.js file.

Best Practices for Global Styles

• Keep Global Styles Minimal: Only define styles that are truly global, such as typography, colors, and layout.
• Use CSS Variables: Use CSS variables to define reusable values, such as colors and spacing.
• Avoid Overwriting Component Styles: Be careful not to overwrite styles defined in individual components.

Secrets and Hidden Facts

• CSS Reset: Use a CSS reset to ensure consistent styling across different browsers.
• Custom Fonts: Use global styles to load custom fonts using @font-face.
• Dark Mode: Use global styles to implement dark mode by toggling CSS variables.

Conclusion

Global styles are an essential part of any web application, allowing you to define styles that apply across the entire application. Whether you’re using a global CSS file, CSS Modules, or Styled-jsx, Next.js provides the tools and flexibility you need to create consistent and maintainable styles.