lsblsblsblsb

<div class="wrapper">

<div class="header">шапка</div>

<div class="menu">меню</div>

<div class="lsb">

<div class="lsb1">сайдбар1</div>

<div class="lsb2">сайдбар2</div>

 </div>

<div class="content">контент</div>

<div class="footer">футер</div>

</div>

.wrapper {display: flex; flex-flow: column nowrap; width:500px; border:1px solid black;}

.lsb1 {width:100px; height:150px; background:palegreen; order:1;}

.lsb2 {width:100px; height:150px; background:khaki; order:1;}

.header {width:100%; height:50px; background:peachpuff;}

.menu {width:100%; height:30px; background:pink;}

.footer {width:100%; height:30px; background:green;}

.lsb { background:whitesmoke; order:1;  

  display: flex; flex-flow: row nowrap; justify-content:space-around;} 

.content { width:100%; height:100px; background:lightcoral;}