Lo he apañado así:
Código HTML:
<!DOCTYPE html>
<html lang="es">
<head>
<meta charset="UTF-8"/>
<title>Document</title>
<link rel="stylesheet" href="style.css"/>
</head>
<body am-panel>
<header>HEADER</header>
<section>
<div am-row>
<div am-cel="one">
<nav am-nav="row">
<a href=""><span>1</span></a>
<a href=""><span>2</span></a>
<a href=""><span>3</span></a>
</nav>
</div>
<div am-cel="five">
body
</div>
</div>
</section>
<footer>FOOTER</footer>
</body>
</html>
Código:
/* style.less */
[am-nav]{
flex: 1;
display: flex;
flex-direction: column;
a{
background-image: linear-gradient(lime, silver);
color: #333;
display: flex;
flex: 1;
span{
flex: 1;
align-self: center;
text-align: center;
}
}
}