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HTML

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Adding Classes

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About the <head>

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Insecure Resource

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CSS

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CSS Base

About CSS Base

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JavaScript

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Babel includes JSX processing.

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HTML 

              
                <link href="//netdna.bootstrapcdn.com/font-awesome/4.1.0/css/font-awesome.min.css" rel="stylesheet">
  <div id="contents">
  <div id="navigation">
    <ul>
      <li><a href=""><i class="fa fa-home"></i><span class="name">menu1</span></a></li>
      <li><a href=""><i class="fa fa-calendar"></i><span class="name">menu2</span></a></li>
      <li><a href=""><i class="fa fa-user"></i><span class="name">menu3</span></a></li>
      <li><a href=""><i class="fa fa-cog"></i><span class="name">menu4</span></a></li>
    </ul>
    <p><a href="javascript:void(0)" class="toggleMenu"><i class="fa fa-angle-left"></i><span class="name">narrow</span></a></p>
  </div>
  <div id="main">
    <h1>Dummy Text</h1>
    <p>
    Natoque facilisi diam quisque aliquam posuere. Pede dolor suspendisse faucibus, primis mi vivamus sagittis mauris tempor torquent, molestie lectus. Leo. Aptent tellus mi mauris Malesuada aenean lectus bibendum.
    </p>
    <p>
    Hac nullam. Integer integer. Facilisi donec. Venenatis Non consequat, cum accumsan. Luctus pulvinar non hendrerit per fames quis.
    </p>
    <p>
    Euismod massa aliquam diam vulputate consectetuer nostra, bibendum auctor ante. Quam. Gravida diam lobortis sapien sociis justo. Tristique augue vehicula sem condimentum euismod ornare.
    </p>
    <p>
    Et sodales elit conubia venenatis sagittis penatibus malesuada. Habitant ligula turpis nisi nulla lacus sagittis leo lorem orci torquent pulvinar rutrum habitant diam dis nibh nibh velit enim ante scelerisque.
    </p>
    <p>
    Natoque facilisi diam quisque aliquam posuere. Pede dolor suspendisse faucibus, primis mi vivamus sagittis mauris tempor torquent, molestie lectus. Leo. Aptent tellus mi mauris Malesuada aenean lectus bibendum.
    </p>
    <p>
    Hac nullam. Integer integer. Facilisi donec. Venenatis Non consequat, cum accumsan. Luctus pulvinar non hendrerit per fames quis.
    </p>
    <p>
    Euismod massa aliquam diam vulputate consectetuer nostra, bibendum auctor ante. Quam. Gravida diam lobortis sapien sociis justo. Tristique augue vehicula sem condimentum euismod ornare.
    </p>
    <p>
    Et sodales elit conubia venenatis sagittis penatibus malesuada. Habitant ligula turpis nisi nulla lacus sagittis leo lorem orci torquent pulvinar rutrum habitant diam dis nibh nibh velit enim ante scelerisque.
    </p>
    <p>
    Natoque facilisi diam quisque aliquam posuere. Pede dolor suspendisse faucibus, primis mi vivamus sagittis mauris tempor torquent, molestie lectus. Leo. Aptent tellus mi mauris Malesuada aenean lectus bibendum.
    </p>
    <p>
    Hac nullam. Integer integer. Facilisi donec. Venenatis Non consequat, cum accumsan. Luctus pulvinar non hendrerit per fames quis.
    </p>
    <p>
    Euismod massa aliquam diam vulputate consectetuer nostra, bibendum auctor ante. Quam. Gravida diam lobortis sapien sociis justo. Tristique augue vehicula sem condimentum euismod ornare.
    </p>
    <p>
    Et sodales elit conubia venenatis sagittis penatibus malesuada. Habitant ligula turpis nisi nulla lacus sagittis leo lorem orci torquent pulvinar rutrum habitant diam dis nibh nibh velit enim ante scelerisque.
    </p>
  </div>
</div>
!

CSS 

              
                @import "compass/css3";

body {
  background-color: #666;
  font-size: 12px;
}
#contents {
  position: relative;
  width: 500px;
  margin: 50px auto;
  overflow: hidden;
}
#navigation {
  position: absolute;
  width: 100px;
  overflow: hidden;
  @include transition(.2s);
  ul {
    margin: 0;
    padding: 0;
    background-color: #fff;
    overflow: hidden;    
    @include box-shadow(0 2px 5px rgba(#000,.5));
    @include border-radius(4px);
  }
  li {
    list-style: none;
    white-space: nowrap;
    a {
      display: block;
      color: #333;
      text-decoration: none;
      &:hover {
        background-color: #ccc;        
      }
    }
  }
  p {
    margin: 0;
    white-space: nowrap;
  }
  a {
    display: block;
    color: #fff;
    text-decoration: none;
  }
  .fa {
    width: 30px;
    height: 30px;
    line-height: 30px;
    text-align: center;
    @include transition(.2s);
  }
  &.narrow {
    width: 30px;
    .name {
      display: none;
    }
  }
}
#main {
  float: left;
  margin-left: 110px;
  padding: 10px 20px;
  background-color: #fff;
  @include box-sizing("border-box");
  @include border-radius(4px);
  @include box-shadow(0 2px 5px rgba(#000,.5));
  @include transition(.2s);
  &.narrow {
    margin-left: 40px;
  }
}

.rotate180 {
	@include transform(rotate(180deg));
}
!

JS 

              
                $(".toggleMenu").click(function(){
  $("#navigation").toggleClass("narrow");
  $("#main").toggleClass("narrow");
  $(this).children(".fa").toggleClass("rotate180");
});
!
999px

Console