title: class name convention in react material-ui framework
body: <p>Is there a class name convention used in material ui library? I'm currently using <a href="https://material-ui-next.com/" rel="noreferrer">material-ui-next</a>. I notice class names like "MuiFormControl-root-124" all over the place with numbers appended to class name. For Paper element "MuiPaper-root-18 MuiPaper-shadow2-22 MuiPaper-rounded-19". I just can't see a pattern here.</p>
  
  <p>Is there a convention which I'm missing. It would be easier to understand this framework if it made sense like Bootstraps grid classes. All help much appreciated. Thank you.</p>