jross
Hi
The shadow style is not from template, your site has 3rd party extension that using same style classes and adding additional style on the template http://prntscr.com/tk8wnq
Because its 3rd party style if i suggest to change code it will also impact other parts where extension used, can you check if the extension style could be turned off or it work only for the pages where the extension is used ?
If no option, you can add this code in custom css
.t4-navbar .navbar { box-shadow: none;}