CSS fix dropdown menu not showing on monitor resolution -

so found out drop down menu on new site not working on different monitor resolutions. wondering if know hows fix css on this.

i able test on laptop , desktop on different display sizes, , following resolutions giving me problems: (not sure if there more): 1600 x 900 1024 x 640 1280 x 720 1280 x 800 2048 x 1152

my site http://livinghealthywithchocolate.com/ , dropdown that's not working under recipes tab. when hover on recipes dropdown menu gets hidden.

thank you!

set high z-index property list items