<box xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
  <stack style="align-items: start; justify-items: left;">
    <label style="margin-top: 33px; margin-left: 33px; color: grey;" value="Hello"/>
    <label style="margin-top: 30px; margin-left: 30px; color: green;" value="Hello"/>
  </stack>
</box>