<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style>
* { box-sizin: border-box;}
html, body { margin: 0; }
.wrapper {
display: table;
width: 100%;
direction: rtl;
text-align: left;
}
.sidebar-left {
width: 25%;
background-color: red;
display: table-cell;
}
.sidebar-right {
width: 25%;
background-color: silver;
display: table-cell;
}
.content {
width: 50%;
background-color: olive;
display: table-cell;
}
@media screen and (max-width: 640px) {
.sidebar-left, .sidebar-right {
display: table-footer-group;
}
}
</style>
</head>
<body>
<div class="wrapper">
<div class="sidebar-right">right</div>
<div class="content">content</div>
<div class="sidebar-left">left</div>
</div>
</body>
</html>
Средний
