Make a fill its parent height, without specifying height on

Answer 1

I found a solution by adding an inner div into each div.Key and using display: table; and display: table-cell; This does what I need. Here is the code:

.Layout {
    width: 1024px; /* TEST */
    height: 480px; /* TEST */
}
.Key {
    text-align: center;
    display: table;
    width: 100%;
    height: 100%;
}
.Key > div {
    display: table-cell;
    vertical-align: middle;
}

And :

<table class="Layout">
    <tbody>
        <tr>
            <td><div class="Key"><div>HEY</div></div></td>
            <td><div class="Key"><div>HEY</div></div></td>
            <td><div class="Key"><div>HEY</div></div></td>
            <td><div class="Key"><div>HEY</div></div></td>
            <td><div class="Key"><div>HEY</div></div></td>
            <td><div class="Key"><div>HEY</div></div></td>
            <td><div class="Key"><div>HEY</div></div></td>
        </tr>
    </tbody>
</table>