<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="css/flexbox-position.css">
    <title>Document</title>
</head>
<body>
    <div class="wrapper">
        <header class="header">
           <div class="block-logo">logo</div>
        </header>
        <section class="content">
           <div class="columns">
              <main class="main">
                 <div class="block-form">Form fields</div>
              </main>
              <aside class="sidebar-first">Sidebar first: Fixed width</aside>
              <aside class="sidebar-second">Sidebar second: Fixed width</aside>
           </div>
        </section>
        <footer class="footer">
           <div class="block-contact-info">Contact info</div>
        </footer>
     </div>     
</body>
</html>