table
{
border-collapse: collapse;
}

td
{
text-align: center;
height:23px;
}

.bl {border-left: 1px solid black; background-color: white}
.br {border-right: 1px solid black; background-color: white}
.bt {border-top: 1px solid black; background-color: white}
.bb {border-bottom: 1px solid black; background-color: white}
.btl {border-top: 1px solid black; border-left: 1px solid black; background-color: white}
.btr {border-top: 1px solid black; border-right: 1px solid black; background-color: white}
.bbl {border-bottom: 1px solid black; border-left: 1px solid black; background-color: white}
.bbr {border-bottom: 1px solid black; border-right: 1px solid black; background-color: white}
.bw {border: 1px solid black; background-color: white}
.bs {border: 1px solid black; background-color: silver}
.bn {border: 1px solid black; color: white; background-color: black}