<!DOCTYPE html>
<html>
<head>
<style>
#main {
width: 220px;
height: 300px;
border: 1px solid black;
display: flex;
align-items: stretch;
}
#main div {
flex: 1;
border: 1px solid black;
display: flex;
align-items: center;
}
</style>
</head>
<body>
<h2>align-items: stretch</h2>
<div id="main">
<div style="background-color:coral;min-height:30px;">RED</div>
<div style="background-color:lightblue;min-height:50px;">BLUE</div>
<div style="background-color:lightgreen;min-height:190px;">Green div with more content.</div>
</div>
</body>
</html>