title: Applying gradient to Material UI's theme background
body: <p>I am trying to make the default background color of the MuiTheme a gradient, I have the following code:</p>
  <pre><code>export const theme = createMuiTheme({
    palette: {
      type: &quot;dark&quot;,
      background: {
        default: &quot;linear-gradient(45deg, #fe6b8b 30%, #ff8e53 90%)&quot;,
      },
    },
  })
  </code></pre>
  <p>However I noticed that material-ui sets it as <code>background-color</code> and gradients are not allowed there.<br />
  Is there a way to bypass this and have it become <code>background</code> instead?</p>