CSS Style for Menu Items from Joomla Menu to Mobile Joomla

Hello,

In Joomla, it is possible to add a custom CSS style when editing an item in Menu Manager.

I've added a custom style for one of my menu items, "redbg".

Despite saving this, the Mobile Joomla site still only renders this line for menu items:
<li class="arrow">
<a href="/index.php/clearance?device=iphone">Clearance</a></li>

If the item is active, it renders
<li class="arrow">
<a href="/index.php/clearance?device=iphone" class="active">Clearance</a></li>

What I want to see is:
<li class="arrow">
<a href="/index.php/clearance?device=iphone" class="redbg">Clearance</a></li>

<li class="arrow">
<a href="/index.php/clearance?device=iphone" class="active redbg">Clearance</a></li>

Any idea how I can do this?

Thanks
Steve