How to style body tag with CSS-in-JS approach?

Question

I am a beginner to CSS-in-JS and emotion, and trying to port a sass react app to emotion. Right from the start I already have the issue of not knowing how to style the body tag.

Do people generally use document.body.style to do this? I can't find this covered anywhere ...

Suppose I want to port following code to emotion, how would that be accomplished?

$bodyFillColor: rgb(218, 236, 236);

body {
  margin: 0;
  padding: 0;
  min-height: 100vh;
  max-width: 100vw;
  background-color: $bodyFillColor;
  .noScroll {
    overflow: hidden;
  }
}

Have any best practices evolved yet that cover this?

Answer 1

With Emotion you can set something up, like the following create-react-app example, to inject global styles:

import React from 'react';
import ReactDOM from 'react-dom';
import { Global, css } from '@emotion/core'

const bodyFillColor = `rgb(218,236,236)`;

class App extends React.Component {
  render() {
    return(
      <div>
        <Global
          styles={css`
            body {
              background: ${bodyFillColor};
              margin: 0;
              padding: 0;
              min-height: '100vh';
              max-width: '100vw';
            }
          `}
        />
        <Global
          styles={{
            'body.noScroll': {
                // Prevent scrolling; conditionally activate this
                // in subcomponents when necessary ...
                overflow: 'hidden',
            },
          }}
        />
      </div>
    );
  }
}

ReactDOM.render(
  <App />,
  document.getElementById('root')
);

This shows an example of injecting a style on the body and also assigning a class to the body that can conditionally be activated later on.

eg.

{this.state.activate && <Global styles={{`stylesetc`}}/>}

https://emotion.sh/docs/globals

Alternative

StyledComponents uses a CSS-in-JS approach and works great with React applications. This is a technique I've used in the past straight from the documentation:

import { createGlobalStyle } from 'styled-components'

const GlobalStyle = createGlobalStyle`
  body {
    color: ${props => (props.whiteColor ? 'white' : 'black')};
  }
`

// later in your app

<React.Fragment>
  <Navigation /> {/* example of other top-level stuff */}
  <GlobalStyle whiteColor />
</React.Fragment>