You can use a little bit of Javascript to add and remove CSS classes of your navitems. For starters, create a CSS class that you're going to apply to the active element, name it ie: ".activeItem". Then, put a javascript function to each of your navigation buttons' onclick event which is going to add "activeItem" class to the one activated, and remove from the others...
It should look something like this: (untested!)
/*In your stylesheet*/
.activeItem{
background-color:#999; /*make some difference for the active item here */
}
/*In your javascript*/
var prevItem = null;
function activateItem(t){
if(prevItem != null){
prevItem.className = prevItem.className.replace(/{\b}?activeItem/, "");
}
t.className += " activeItem";
prevItem = t;
}
<!-- And then your markup -->
<div id='nav'>
<a href='#abouts' onClick="activateItem(this)">
<div class='navitem about'>
about
</div>
</a>
<a href='#workss' onClick="activateItem(this)">
<div class='navitem works'>
works
</div>
</a>
</div>