<!DOCTYPE html>
<html lang="en">
<head>
<title>Learn CSS</title>
</head>
<body>
<div class="flex-parent">
<div class="inside-flex item"> <div> Flex Item 1 </div></div>
<div class="inside-flex double"> <div> Flex Item 2 </div></div>
<div class="inside-flex item"> <div> Flex Item 3 </div></div>
</div>
</body>
</html>