Try it Editor: CSS align-items Property

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<!DOCTYPE html>
<html>
<head>
<style> 
#main {
    width: 220px;
    height: 300px;
    border: 1px solid black; 
    display: -webkit-flex; /* Safari */
    -webkit-align-items: center; /* Safari 7.0+ */
    display: flex;
    align-items: center;
}

#main div {
   -webkit-flex: 1; /* Safari 6.1+ */
   flex: 1;
}
</style>
</head>
<body>

<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>

<p><b>Note:</b> Internet Explorer 10 and earlier versions do not support the align-items property.</p>

<p><b>Note:</b> Safari 7.0 to 9.0 supports an alternative, the -webkit-align-items property.</p>

</body>
</html>
Result :