.out
{
    display: block;
    background: #bbb;
    border: 1px solid #ddd;
    position: relative;
    margin: 1em 0;
}
/*设置外框(背景、边框与定位)*/


.in2
{
    display: block;
    background: #777;
    border: 1px solid #999;
    position: relative;
    padding: 1px;
    margin: 1px;
}

.in
{
    text-align: center;
    background: #fff;
    border: 1px solid #555;
    position: relative;
    padding: 5px;
    font-weight: normal;
}
/*内框的设定*/

.ltin
{
    left: -5px;
}

.tpin
{
    top: -5px;
}

.rtin
{
    left: 5px;
}
/*内框移位，外框的背景色就成了阴影*/