Question

I need a child div to be as high as its parent, but I do not know the parent’s height. It can change.
Setting “height: 100%” does not work, as the div will take the height of the entire page.

This is the layout of the divs:

<div id="deelnemersballoon">
    <div class="balloonarrow"></div>

    <div class="balloonborder">

        <div class="ballooncontent">
            <div id="aantaldeelnemers">1</div>
            <div id="deelnemertekst">deelnemer werd toegevoegd.</div>
            <div class="clear">
                <button>Add something</button>
            </div>
        </div>

    </div>

</div>

.balloonarrow should be as high as #deelnemersballoon

Answer 1

set parent div height in pixels (for ex height:100px ) and set child as 100% (height:100%) . Child only occupies parent div width fully