how does media create emotion code example

Example: how to use media queries in emotion

/** @jsx jsx */
import { jsx, css } from '@emotion/core'

render(
  <p
    css={css`
      font-size: 30px;
      @media (min-width: 420px) {
        font-size: 50px;
      }
    `}
  >
    Some text!
  </p>
)