div.left7 {
    float: left;
    width: 50%;
    color: #006;
    background: #fff;
    margin: -8px 5px 0 -5px;
    border-width: 0 3px 3px 0;
    border-style: solid;
    border-color: #f00;
    padding: 8px 5px 5px 8px;
}
html>body div.left7 {
    margin-left: -8px;
}
div.right7 {
    color: #600;
    background-color: #ccc;
    border: 3px #f00 solid;
    padding: 5px 5px 5px 6px;
}
html>body div.right7 {
    padding-left: 5px;
}