.ntb {border: 1px solid #000000; border-top:0px none; }
.nlb {border: 1px solid #000000; border-left:0px none; }
.nrb {border: 1px solid #000000; border-right:0px none; }
.nbb {border: 1px solid #000000; border-bottom:0px none; }
.nb {border: 0px none;}
.ab {border: 1px solid #000000; }