I can not get the header to display properly on laptop or smaller device. Please help: http://web-design-demo.net/home.html Thank you

Product page overlaps the header - I have tried Z-index already, am i missing something else ? https://trinitydirect.com.au/index.php/tiles/wall-tiles/quadro-56.html http://prntscr.com/fvn6xm

As shown at below screen shot - drop down menu of horizontal menu gets overlapped by content ? - how do i stop happening this ? http://prntscr.com/fus2ke