[sourcecode language="css"]
@the-border: 1px;
@base-color: #111;

#header {
color: @base-color * 3;
border-left: @the-border;
border-right: @the-border * 2;
}

#footer {
color: (@base-color + #111) * 1.5;
}

ul
{
list-style-type: none;
height: 30px;

li
{
float: left;
padding-right: 15px;

a
{
padding: 5px;
display: block;
color: black;
text-decoration: none;
}

a:hover
{
background-color: @menu_color - #222;
}
}
}

[/sourcecode]

Curious? 4GuysFromRolla has a nice article about .LESS

btw, if you're not doing ASP.NET, you can create css from .less by using the command line compiler:

dotless.Compiler.exe -m Styles.less Styles.css