Isolated styled-components with @font-face

And on the other side of the same coin in Chrome:

do not use @font-face inside injectGlobal if using e.g. react-router. You will get re-paint of all of you app on each newly loaded route. And this is why:

Same font-files downloaded on each new route. As soon as you include font-face in a separate .css file - problem solves as stated in the last comment in this github issue.

injectGlobal is deprecated. Use createGlobalStyle

import { createGlobalStyle } from 'styled-components'

export const GlobalStyle = createGlobalStyle`  
  body {
    font-family: 'Muli', sans-serif;

    h1 {
      font-weight: 800;
      font-size: 36px;

    p {
      font-size: 18px;
    }
  }
`;

Then you can use it in your App.js:

import { GlobalStyle } from './styles/global'

class App extends Component {
  render() {

    return (
      <ThemeProvider theme={theme}>
        <>
          <GlobalStyle/>
          <Container/>
        </>
      </ThemeProvider>

    )
  }
}

That's exactly why we made injectGlobal. If you take a look at our docs they say:

We do not encourage the use of this. Use once per app at most, contained in a single file. This is an escape hatch. Only use it for the rare @font-face definition or body styling.

So what I'd do is create a JS file called global-styles.js which contains this code:

// global-styles.js

import { injectGlobal } from 'styled-components';

injectGlobal`
  @font-face {
     font-family: 'My custom family';
     src: url('my-source.ttf');
  }
`

As you can see, all we do here is inject some global styling-in this case @font-face. The last thing necessary to make this work is to import this file in your main entry point:

// index.js

import './global-styles.js'

// More stuff here like ReactDOM.render(...)

This will mean your font-face is only injected once, but still all of your components have access to it with font-family: 'My custom family'!

Doing it this way will give you a flash-of-invisible-text (FOIT), but that has nothing to do with styled-components-it'd be the same if you were using vanilla CSS. To get rid of the FOIT requires a more advanced font loading strategy rather than just @font-faceing.

Since this has nothing to do with styled-components, I highly recommend watching these two Front End Center episodes to learn more about how to best do this: "Crafting Web Font Fallbacks" and "The Fastest Webfont Loader in the West"!