It is the following lines that break the design (lines 1642-1653) of the front.css file. I commented them out and now it works again, but that is nothing but a workaround.
/* fieldset {
border: 1px solid #dddddd !important;
padding: 10px;
border-radius: 3px;
}
legend {
font-weight: bold;
font-size: inherit; color: inherit;display: inline;float: left;padding: 10px !important;
border-bottom: 1px solid #dddddd !important;
} */