<!DOCTYPE html>
<html>
<head>
<style>
.flex-container {
display: -webkit-flex;
display: flex;
-webkit-flex-flow: row wrap;
flex-flow: row wrap;
font-weight: bold;
text-align: center;
}
.flex-container > * {
padding: 10px;
flex: 1 100%;
}
.main {
text-align: left;
background: cornflowerblue;
}
.header {background: coral;}
.footer {background: lightgreen;}
.aside1 {background: moccasin;}
.aside2 {background: violet;}
@media all and (min-width: 600px) {
.aside { flex: 1 auto; }
}
@media all and (min-width: 800px) {
.main { flex: 3 0px; }
.aside1 { order: 1; }
.main { order: 2; }
.aside2 { order: 3; }
.footer { order: 4; }
}
</style>
</head>
<body>
<div class="flex-container">
<header class="header">Header</header>
<article class="main">
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Quisque sed ex turpis. Cras luctus nibh lectus, in ullamcorper ex tempor eleifend. Nulla bibendum, eros a consequat vestibulum, orci massa fermentum quam, sed commodo nunc ex vitae nisl. Aliquam ullamcorper interdum est nec tincidunt.</p>
</article>
<aside class="aside aside1">Aside 1</aside>
<aside class="aside aside2">Aside 2</aside>
<footer class="footer">Footer</footer>
</div>
</body>
</html>