Introduction to Design Systems

Adding global styles

There is a way to add global styles to our styled components, which we'll want to do for things such as defining our root font size.

First, let's install a helper package called polished. This gives us some great features, one of which we'll use right now: normalize.

Let's install the package.

npm i polished

Inside of the utils/ directory, create a new file called Global.js. Let's add the following.

import { createGlobalStyle } from "styled-components";
import { primaryFont } from "./typography";
import { normalize } from "polished";

export const GlobalStyle = createGlobalStyle`
html {
  box-sizing: border-box;
  font-size: 16px;
*, *:before, *:after {
  box-sizing: inherit;
body {
  margin: 0;
  font-family: ${primaryFont};
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;

main {
  width: 90%;
  margin: 0 auto;

Add Global.js to the default export in index.js.

export * from "./Global";

Back inside index.js let's import our global styles and render it as a self-closing tag at the end of our JSX.

import { GlobalStyle } from "./utils";

const App = () => (
    <PrimaryButton>Hello World</PrimaryButton>
    <SecondaryButton>Goodbye World</SecondaryButton>
    <GlobalStyle />

ReactDOM.render(<App />, document.querySelector("#root"));