index.js

import React from 'react'
import System from 'system-components/dist/System'
import styled from 'react-emotion'

const sys = new System({
  createComponent: type => (...styles) => styled(type)(...styles)
})

const Heading = sys({
  fontSize: 5,
  color: 'tomato'
})

export default props =>
  <Heading bg='black'>
    Hello emotion + system-components
  </Heading>

package.json

{
  "private": true,
  "name": "emotion-system-components",
  "scripts": {
    "start": "npx @compositor/x0 . --open"
  },
  "dependencies": {
    "emotion": "^9.2.3",
    "react": "^16.4.0",
    "react-emotion": "^9.2.3",
    "system-components": "^2.0.4"
  }
}