Box überlagert!

#content {
    background: #ebebeb url(../img/content_hintergrund.png) repeat-y;
    width: 910px;
    margin: 0 auto;
    padding: 0 25px 20px 25px;
    }




#contentboxlinks {
    background: transparent;
    width: 290px;
    margin: 20px 10px auto auto;
    float: left;
    }


#contentboxmitte {
    background: transparent;
    width: 290px;
    margin: 20px 10px auto 10px;
    float: left;
    }


#contentboxrechts {
    background: transparent;
    width: 290px;
    margin: 20px auto auto 10px;
    float: left;
    }

<div id="contenttop"></div>
        <div id="content">
            <div id="contentboxlinks">
                <h2 class="boxueberschrift">Überschrift h2</h2>
                    <hr class="contentboxtrennlinie" />
                        <p>
                        Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. 
                        </p>
            </div>

            <div id="contentboxmitte"></div>
                <div class="profilbild"></div>

            <div id="contentboxrechts"></div>

            <br clear="left" />

        </div>