Just enhance the second css with “height ….” and you will get a wonderful, wonderful mega menu in smartmenu. The height is unfortunately fixed in this solution. Got no solution for a variable height, depending on the number of menu items – maybe someone else :o) .
#main-menu > li {
position:static !important;
}
#main-menu > li > ul {
margin-left:0 !important;
right:0 !important;
width:auto !important;
max-width:none !important;
height: 100px;
-webkit-column-count: 6;/*6= number of columns you like to have in your mega menu*/
-moz-column-count:6;
column-count: 6;
}