Currently trying to use inlined "display: none;" doesn't work for Gmail, so here's the best workaround (of about 3 different approaches I tried).

gmail_display_none_workaround.html

<!-- 
  You can't do position absolute + visibility/opacity in gmail
  display: none; only works if you inline it as !important, but then this destroys the functionality for 
  all other clients, this workaround has been working wonders for us!!!
 -->
<style>
  div.gmail {  
    display: block;
    width: 0;
    overflow: hidden;
    float: none;
    height: 0;
    max-height: 0;
  }

  @media only screen and (max-width: 600px) {

    table[class="body"] div.gmail {  
      display: block !important;
      width: auto !important;
      overflow: visible !important;
      float: none !important;
      height: inherit !important;
      max-height: inherit !important;
    } 
    
  }
</style>

<!--[if !mso]><!-->

  <div class="gmail">
    <!-- This workaround is only viable when #gmail's next direct descendant is a table -->
  </div>

<!--<![endif]-->