To make the below design switch with css

Remove current bold

.listing_detail strong{
font-weight:300;
}

Add bold to the field value

.listing_detail {
    padding: 3px 0px;
    font-weight: 800;
}

You can make the font-weight value different. These are just examples. These are possible options http://www.htmldog.com/references/css/properties/font-weight/