- Go back to Appearance > Menus.
- Click on the caret on the top-right of menu item that contains the megamenu subitem to expand it.
- In the CSS Classes text box, enter yamm-hw.
- This will make the subitem extend to half-width of the container.
- If the CSS Classes field is not visible. Click on Screen Options on the top-right corner of the screen and check on CSS Classess under Show advanced menu properties.
- Click on Save Menu.
megamenu dropdown as Half of the width Output