ember.js - Fixed header title is not displayed correctly -

i'm using fixed header material design lite have weird issue:

on chrome:

on firefox:

<header class="mdl-layout__header">    <div class="mdl-layout__header-row">      <!-- title -->      <span class="mdl-layout-title">example website</span>    </div>  </header>

i'm using emberjs frontend. here jsfiddle basic configuration , issue : https://jsfiddle.net/c3f6yg8z/

am doing wrong ?

thanks, gabriel