<div class="column grid_12"><p>12</p></div>

OFFS, people. You've got an excellent CSS preprocessor with mixin capability here, use it. Do something like this:

    #sidebar {
        .column;
        .grid_12;
        // other styling
    }

and then this:

   <div id="sidebar"><p>twelve</p></div>

It's easy, clean, and doesn't maul your markup.