Each one individually where each one that drops will be a different width, such as Hem Sub-cats dropping down to be 12em wide, while Information Sub-cats drop down to be 14em wide?............. then........No. Sorry.
But......you CAN control it on a whole Level functionality, though......So..........if you're just wanting to make each one of your White dropdown parts as wide as your Blue "buttons", then Yes. Find these sections in the css:
div#dropMenu ul ul li {/*border: 1px solid #CCC;*/width:14em;z-index:1000;}
and:
div#dropMenu ul.level1 li.submenu:hover ul.level2,
div#dropMenu ul.level2 li.submenu:hover ul.level3,
div#dropMenu ul.level3 li.submenu:hover ul.level4,
div#dropMenu ul.level4 li.submenu:hover ul.level5,
div#dropMenu ul.level5 li.submenu:hover ul.level6,
div#dropMenu ul.level6 li.submenu:hover ul.level7,
div#dropMenu ul.level7 li.submenu:hover ul.level8 {position: absolute; width: 14em;display:block;z-index:1000;}
And change the width in BOTH of those to 14em. That should make those levels as wide as your buttons.
Now, when you do that, then it's going to stack your 3rd level on top of your 2nd level. So, you'll want to find this section and edit it to be 14em, also:
div#dropMenu ul.level3,
div#dropMenu ul.level4,
div#dropMenu ul.level5,
div#dropMenu ul.level6,
div#dropMenu ul.level7,
div#dropMenu ul.level8{top: 0; left: 12em; background:#fff;}
That will push the 3rd level over to the edge of the 2nd level.
Hope this helps.