fight magin collapsing

margincollapsed.css

/*
** http://jsfiddle.net/hEDEK/1/
**
** http://www.w3.org/TR/CSS21/box.html#collapsing-margins
*/
.child {
    background: red;
    width: 30px;
    height: 30px;
    margin: 10px;
}

.wrapper {
    /* pushing our child element to other block-formatting context */
    overflow: hidden;
}

margincollapsed.html

<div class="wrapper"><div class="child">1</div></div>
<div class="wrapper"><div class="child">2</div></div>
<div class="wrapper"><div class="child">3</div></div>
<div class="wrapper"><div class="child">4</div></div>