In the CoolMart things are little different, the dropdown menu width is limited automatically depends on your website width size (the width of your entire website, which is usually 900px or 1000px).
Because the dropdown menu can't overfload the website, it's total width must equal to website's width. Therefore each column get its own share.
You may consider disabling the module from the dropdown menu on the right side (module position: dropdownmenuChild-1). It will give you lots of extra space, because the module inside the dropdown menu gets double width size comparing the regular menu items' columns.
Another way of increasing the width side of columns is to increase the width of the entire template (which is not recommended, don't enlarge the website width size more than 1000px for better user experience)
Regards.