我有以下代码：

<div class="table">
    <div class="row">
        <div class="cell">Cell</div>
        <div class="cell">Cell</div>
    </div>
    <div class="row">
        <div class="cell colspan2">Cell</div>
    </div>
</div>

<style>
    .table {
        display: table;
    }
    .row {
        display: table-row;
    }
    .cell {
        display: table-cell;
    }
    .colspan2 {
        /* What to do here? */
    }
</style>

非常简单。如何为带有的元素添加colspan（或等价的colspan）display: table-cell？