Shop subitems are created using mega menu option. Our services menu item use the drop-down design type. So, you need to change the design type to Mega menu, choose the min number of columns (2) and reduce the default 2 columns with to 252px if you don’t plan more than 1 column for this item http://prntscr.com/mlgr6h , after that edit the subitem options and choose 100% width http://prntscr.com/mlgs6m
Check the frontend.
