XF 1.5 Menu in responsive design

Then its a problem with ad code, not with menu. Probably its floating without proper clearing. Wrap your ad code in div with style="overflow:hidden".
 
Solution:

navigation template.

Code:
<!-- responsive popup -->
        <li class="navTab navigationHiddenTabs Popup PopupControl PopupClosed" style="display:none">   
                       
            <a rel="Menu" class="navLink NoPopupGadget"><span class="menuIcon">{xen:phrase menu}</span></a>
           
            <div class="Menu JsOnly blockLinksList primaryContent" id="NavigationHiddenMenu"></div>
        </li>
 
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