how to position div on the bottom of another div?

Need to set <div id="group-of-tables"> to the bottom of the <div class="item-content">:

  <div class="item-content">
        <div id="group-of-tables">
            <table class="item" id="first-table">
                <tr>
                    <td><div class="" id="">1</div></td>
                    <td><div class="" id="">2</div></td>
                    <td><div class="" id="">3</div></td>
                    <td><div class="" id="">4</div></td>
                </tr>
            </table>
            <table class="item" id="second-table" border="1">
                <tr>
                    <td><div class="" id="">Next</div></td>
                </tr>
            </table>
        </div>
    </div>

Css:

div.item-content{
height:100%;
}

Something like this:

But without absolute position