   <button hidden id="sign-in" class="mdl-button mdl-js-button mdl-js-ripple-effect mdl-color-text--white">
          <i class="material-icons">account_circle</i>Sign-in with Google
        </button>
      </div>
    </div>
  </header>

  <main class="mdl-layout__content mdl-color--grey-100">
    <div id="messages-card-container" class="mdl-cell mdl-cell--12-col mdl-grid">

      <!-- Messages container -->
      <div id="messages-card" class="mdl-card mdl-shadow--2dp mdl-cell mdl-cell--12-col mdl-cell--6-c