CodePen

HTML

            
              <!doctype html>
<html lang="en">
  
<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <title>Responsive Design</title>
</head>
  
<body>
  
  <header class="main-header">
    <img src="http://placehold.it/400x250" alt="Image" />
    
    <nav>
      <ul>
          <li class="active"><a href="#">Home</a></li>
          <li><a href="#">About</a></li>
          <li><a href="#">Clients</a></li>
          <li><a href="#">Contact Us</a></li>
      </ul>
    </nav>  
  </header>
  
  <div class="content-wrap">
    
    <div class="left-contents">
      
    <div class="content-module">
      <article>
        <h2><a href="#">Sample Blog Title</a></h2>
        <p class="meta-data">Post published by Steven</p>
        <p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p>
        <p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p>  
      </article>
    </div><!-- content end -->
    
    <div class="content-module">
      <article>
        <h2><a href="#">Sample Blog Title</a></h2>
        <p class="meta-data">Post published by Steven</p>
        <p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p>
        <p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p>  
      </article>
    </div><!-- content end -->
      
    </div><!-- left contents end -->
  
  <aside class="sidebar-module">
    <article>
      <h2>Top Sidebar</h2>
<p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante.</p>  
    </article>
  </aside>
  
  <aside class="sidebar-module">
    <article>
      <h2>Middle Sidebar</h2>
<p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante.</p>  
    </article>
  </aside>
  
  <aside class="sidebar-module">
    <article>
      <h2>Bottom Sidebar</h2>
<p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante.</p>  
    </article>
  </aside>
    
        
  </div><!-- main-content end -->
  
  <div class="clear"></div>
  
  <footer>
    <p>Copyright &copy; 2013. <a href="#">Steven Watson</a></p>
  </footer>
  
</body>
</html>
            
          
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via HTML Inspector

CSS

            
              *, :after, :before {
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
}

.clear {
  clear: both;
}

body {
  background: url('http://subtlepatterns.com/patterns/witewall_3.png');
  font-size: 87.5%; /* Base font is 14px */
  font-family: Arial, Helvetica, sans-serif;
  line-height: 1.5em;
  text-align: left;
  margin: 0 auto;
  width: 70%;
  clear: both;
}

a {
  text-decoration: none;
}

a:link, a:visited {
  color: #666;
}

a:hover, a:active {
  color: #cf5c3f;
}

.main-header img {
  height: auto;
  margin: 2% 0;
}

.main-header nav {
  background-color: #666;
  height: 40px;
  -webkit-border-radius: 5px;
  -moz-border-radius: 5px;
  border-radius: 5px;
}

.main-header nav ul {
  list-style: none;
  margin: 0 auto;
}

.main-header nav ul li {
  float: left;
  display: inline;
}

.main-header nav a:link, .main-header nav a:visited {
  color: #fff;
  display: inline-block;
  padding: 10px 25px;
  height: 40px;
}

.main-header nav a:hover, .main-header nav a:active, .main-header nav .active a:link, .main-header nav .active a:visited {
  background-color: #cf5c3f;
  text-shadow: none;
}

.content-wrap {
  margin: 2% 0;
  overflow: hidden;
}

.left-contents {
  float:left;
  width:70%;
}

.content-module {
  -webkit-border-radius: 5px;
  -moz-border-radius: 5px;
  border-radius: 5px;
  background-color: #fff;
  padding: 3% 5%;
  margin: 0 0 2% 0;
}

.meta-data {
  font-style: italic;
  color: #999;
  font-size: 85%;
}

.sidebar-module {
  -webkit-border-radius: 5px;
  -moz-border-radius: 5px;
  border-radius: 5px;
  padding: 2% 3%;
  background: #fff;
  width: 28%;
  margin: 0 0 2% 2%;
  float: left;
}

footer {
  background: #666;
  border-top: 5px solid #CF5C3F;
  height: 40px;
}

footer p {
  width: 92%;
  margin: 6px auto;
  color: #fff;
}
            
          
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