CSS Menu – Dropdowm menu

I have a basic menu with 5 drop downs. The last drowpdowm menu is a bit off the browser and what I want to do is adjust the width just for that menu and move the drop down a bit more to the left. Here is the CSS any help would be much appreciated.

/* Drop Down menu*/

.menu > li > .sub-menu {
display: block;
position: absolute;
z-index: 999;
background-color: #111c3c;
font: 14px ‘proxima_nova_rgregular’, Arial, sans-serif;
color: #fff;
-webkit-border-radius: 4px;
-webkit-border-top-left-radius: 0;
-moz-border-radius: 4px;
-moz-border-radius-topleft: 0;
border-radius: 4px;
border-top-left-radius: 0;
-webkit-box-shadow: 3px 3px 5px 0px rgba(0, 0, 0, .25);
box-shadow: 3px 3px 5px 0px rgba(0, 0, 0, .5);
overflow:hidden;
text-transform: none;

width:250px;
visibility:hidden;
opacity:0;
padding: 10px 5px;
}

I was trying to use this to control the last menu but is not working, I read about using child but not sure how to do this

.menu > li > .sub-menu > .menu-item-21{
width: 100px;
left:-150px;
}