how to have divs line up when on mobile code example

Example: put divs in rows and colums

//html

<div class="Row">
    <div class="Column">C1</div>
    <div class="Column">C2</div>
    <div class="Column">C3</div>
</div>

//css

.Row {
    display: table;
    width: 100%; /*Optional*/
    table-layout: fixed; /*Optional*/
    border-spacing: 10px; /*Optional*/
}
.Column {
    display: table-cell;
    background-color: red; /*Optional*/
}