/**
 * Grid
 */
#grid{

    /* Vertical grid lines */
    background: url(/pix/v-grid.png) repeat-y 0 0;

    /* Dimensions - same width as your grid with gutters */
    width: 960px;

    /* Grid (left-aligned)
    position: absolute;
    top: 0;
    left: 0;
    */

    /* Grid (centered) */
    position: absolute;
    top: 0;
    left: 50%;
    margin-left: -480px;

}

/**
 * Horizontal grid lines, defined by your base line height
 *
 * Remember, the CSS properties that define the box model:
 * visible height = height + borders + margins + padding
 */
#grid div.horiz{

    /* 20px line height */
    height: 13px;
    border-bottom: 1px dotted #aaa;
    margin: 0;
    padding: 0;

}