<!DOCTYPE html>
<link rel="author" title="Sergio Villar Senin" href="mailto:svillar@igalia.com">
<link href="support/flexbox.css" rel="stylesheet">
<style>
.flex-item {
    flex: 1 0 auto;
    height: 100%;
    border: 1px solid blue;
}
</style>

<div class="flexbox">
    <div class="flexbox column">
        <div class="flex-item">
            <div>AAA</div>
        </div>
        <div class="flex-item">
            <div>BBB</div>
        </div>
    </div>
</div>