Lines in the middle of the squares

.cellContent{
  border-right: 1px solid #000000; 
  border-bottom: 1px solid #000000; 
  float: left; 
  margin:10px;
  width: 100px; 
  height: 100px;  
  font-weight: 400;
  background: #8a97a0;
  color: #FFF;
}
.row { 
  clear: both; 
  overflow: hidden; 
  width: auto;
}
.table {
  margin: 20px;
  width: 450px;
  display: inline-block;
}
.row:not(:first-child){
  border-top: 1px solid lightgrey;
}
.cell:not(:first-child){
  border-left: 1px solid lightgrey;
}

<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js" integrity="sha384-UO2eT0CpHqdSJQ6hJty5KVphtPhzWj9WO1clHTMGa3JDZwrnQq4sF86dIHNDz0W1" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js" integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" crossorigin="anonymous"></script>
<div class="table">
    <div class="row">
        <div class="cell">
          <div class="cellContent">
          &nbsp;
          </div>
        </div>
        <div class="cell">
          <div class="cellContent">
          &nbsp;
          </div>
        </div>
        <div class="cell">
          <div class="cellContent">
          &nbsp;
          </div>
        </div>
        <div class="cell">
          <div class="cellContent">
          &nbsp;
          </div>
        </div>
    </div>
    <div class="row">
        <div class="cell">
          <div class="cellContent">
          &nbsp;
          </div>
        </div>
        <div class="cell">
          <div class="cellContent">
          &nbsp;
          </div>
        </div>
        <div class="cell">
          <div class="cellContent">
          &nbsp;
          </div>
        </div>
        <div class="cell">
          <div class="cellContent">
          &nbsp;
          </div>
        </div>
    </div>
    <div class="row">
        <div class="cell">
          <div class="cellContent">
          &nbsp;
          </div>
        </div>
        <div class="cell">
          <div class="cellContent">
          &nbsp;
          </div>
        </div>
        <div class="cell">
          <div class="cellContent">
          &nbsp;
          </div>
        </div>
        <div class="cell">
          <div class="cellContent">
          &nbsp;
          </div>
        </div>
    </div>
    
</div>