title: How to set custom spacing margin value in Material UI Grid
body: <p>I need to set specific spacing value between Grid items in Material UI.
  Bellow is the code I have:</p>
  <pre><code>&lt;Grid container spacing={1}&gt;
      &lt;Grid item xs={6}&gt;Node 1&lt;/Grid&gt;
      &lt;Grid item xs={6}&gt;Node 2&lt;/Grid&gt;
      ...etc
  &lt;/Grid&gt;
  </code></pre>
  <p>The problem is the margin when I set <code>spacing={1}</code> is a little bigger than what I want. How can I set custom value for margin between items?</p>