Still working on nav menu drop-down menus and sub-menus. I've got them the way I want on large screens but not when the nav menu collapses for small devices. The nav bar containing the "hamburger" icon extends the full width of the screen which is fine. But the drop-down menus and sub-menus also extend across the screen instead of the width required for the contents. I've tried many schemes but I haven't hit on the right html or css to get what I want. The drop-down menus and sub-menus open down as expected.

How can I keep drop-down menus and sub-menus from extending across the entire screen when the nav menu is collapsed?