<html>
<head>
<style>
#main {
width: 300px;
height: 300px;
border: 1px solid black;
display: flex;
}
#main div {
flex: 1;
}
</style>
</head>
<body>
<h1>The flex Property</h1>
<div id="main">
<div style="background-color:coral;">RED</div>
<div style="background-color:lightblue;">BLUE</div>
<div style="background-color:lightgreen;">Green div with more content.</div>
</div>
</body>
</html>