Ups, small mistake:
#form-legend {
background: #d0d0d0;
text-align:center;
font-weight:bold;
width: 100%;
padding: 5px;
}
and I made the left side label look a little bit like the old style:
.margin-form .form-item-wrapper .form-label {
float: left;
text-align: right;
display: block;
width: 15em;
background-color: #e9e9e9;
padding: 5px;
}
It is not perfect, but for text fields it is remarkably close.