.picturelist
{
width:600px;
text-align: center;
}

.picturelist_left
{
float:left;
width:50px;
height:100px;
background-image: url(../prev.png);

}

.picturelist_right
{
float:left;
width:50px;
height:100px;
background-image: url(../next.png);
}

.picturelist_holder
{
float: left;
width: 500px;
}

.picturelist_holder img
{
margin:auto;
}