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>

Answer 2

If you're using react application you can create index.css file and set your wanted properties for the body. Then you must import the index.css file in your index.js file and the changes will take place.