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Production build returns multiple styles

See original GitHub issue

Current behavior:

I use Emotion with “@emotion/babel-preset-css-prop”. In production environment Emotion creates multiple style tags. This is desired for the dev environment, but not for production.

To reproduce:

For testing purposes I have created a simple React component.

class Welcome extends React.Component {
  render() {
    return (
      <div css={{ backgroundColor: 'red' }}>
        <div css={{ color: 'yellow'}}>Yellow div</div>
    );
  }
}

In the .babelrc within the production env, I have added within the presets at the first place the @emotion/babel-preset-css-prop.

"production": {
  "presets": [
    ["@emotion/babel-preset-css-prop"],
    [
      "@babel/preset-env",
      {
        "useBuiltIns": false,
        "targets": {
          "browsers": ["last 2 versions"]
        },
        "debug": false
      }
    ],
    ["@babel/preset-typescript"],
    "@babel/preset-react"
  ],
  "plugins": [ .... ]

I get one global stylesheet file, but each css styling gets rendered in a new style tag within the html head. This is on purpose for the dev build, but not for production mode.

Given the component above my head looks as following:

<style data-emotion="css-global"></style>
<style data-emotion-css="f5yfbg">.css-f5yfbg{background-color:red;}</style>
<style data-emotion-css="fsfbn2">.css-fsfbn2{color:yellow;}</style>

I read all issues regarding to Emotion, but I couldn’t find something similiar.

Expected behavior:

Emotion should render one single stylesheet file.

Environment information: