table.operation{
  border: 0px solid black;
  border-collapse: collapse;
}
.operation tr:last-child{
  border-top: 1px solid black;
}
.operation td{
  text-align: right;;
}
.operation .sign{
  padding-right: 5px;
}
.operation.multiplication tr:last-child, .operation.division tr:last-child{
  border-top: none;
}
.operation.division td{
	padding: 0px 3px; 
}
.operation.division tr:first-child td:last-child{
	border-left: 1px solid black;
	border-bottom: 1px solid black;
}

.operation.division td{
	text-align: left;
}