Hi,
Here is a basic example. Of course, you will need to add more styles for the headings, links, etc. but the layout part should be OK:
HTML:
...
<li><a href="#">Mega menu</a>
<ul class="mega-menu">
<li>
<div class="row">
<div class="col">
<h2>Heading</h2>
<ul>
<li><a href="#">Link</a></li>
<li><a href="#">Link</a></li>
<li><a href="#">Link</a></li>
</ul>
</div>
<div class="col">
<h2>Heading</h2>
<ul>
<li><a href="#">Link</a></li>
<li><a href="#">Link</a></li>
<li><a href="#">Link</a></li>
</ul>
</div>
</div>
</li>
</ul>
</li>
...
CSS:
.mega-menu .row {
width: 500px;
max-width: 100%;
}
.mega-menu .row:after {
content: '';
display: block;
clear: both;
height: 0;
overflow: hidden;
}
.mega-menu .col {
float: left;
padding: 10px;
width: 50%;
}
.mega-menu, .mega-menu ul {
width: auto !important;
min-width: 0 !important;
max-width: none !important;
}
.mega-menu ul {
position: static;
display: block !important;
}
.mega-menu ul li {
/* ... */
}
.mega-menu ul a {
/* ... */
}
Cheers!