#art {
  display: table;
  border-spacing: 1px;
  background-color:black;
  border: 5px solid blue;
}

.row{
  display:table-row;
}

.pixel{
  display:table-cell;
  background-color:white;
  width:20px;
  height:20px;
}

.pen{
  display: inline-block;
  width:20px;
  height:20px;
  border: 2px solid black;
}