CSS table colspan

HTML

<div class="table">
    <div class="table-row">
        <div class="table-cell">
            top left cell
        </div>
        <div class="table-cell">
            top right cell
        </div>
    </div>
    <div class="table-row-group">
        <div class="colspan">
            Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
        </div>
    </div>
    <div class="table-row">
        <div class="table-cell">
            bottom left cell
        </div>
        <div class="table-cell">
            bottom right cell
        </div>
    </div>
</div>

CSS

.table {
    display: table;
    table-layout: fixed;
    width: 100%;
    border-collapse: collapse;
}

.table-row {
    display: table-row;
    border-collapse: collapse;
}

.table-cell {
    display: table-cell;
    padding: 5px;
    border: 1px solid black;
}

.table-row-group{
  display: table-row-group;
  border-collapse: collapse;
  border:1px solid grey;
  box-sizing: border-box;
}

.table-cell.colspan {
   display: table-caption; 
   text-align: center;
    margin-top: -1px;
    margin-bottom: -1px;