title: Div margin problems
body: <p>I have a div element of <code>width:90%;</code> and <code>margin: 80px auto;</code>. The html has a fixed background image. When I added a link to bootstrap, the left and right margins of the div filled in with white. How to solve this problem?</p>
  
  <pre><code>&lt;div class="header-container"&gt;
      &lt;div class="logo"&gt;
          &lt;header&gt;
              &lt;h5&gt;royal apartments for you&lt;/h5&gt;
                  &lt;ul id="menu"&gt;
                    &lt;li&gt;&lt;a href="index.html"&gt;Main&lt;/a&gt;&lt;/li&gt;
                    &lt;li&gt;&lt;a href="#"&gt;Apartments&lt;/a&gt;&lt;/li&gt;
                    &lt;li&gt;&lt;a href="#"&gt;Services&lt;/a&gt;&lt;/li&gt;
                    &lt;li&gt;&lt;a href="#"&gt;Blog&lt;/a&gt;&lt;/li&gt;
                    &lt;li&gt;&lt;a href="#"&gt;Contacts&lt;/a&gt;&lt;/li&gt;
                  &lt;/ul&gt;
          &lt;/header&gt;
      &lt;/div&gt;
      &lt;div class="slider"&gt;
  
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>CSS:</p>
  
  <pre><code>html { 
    background: url(images/146987895643799.jpg) no-repeat center center fixed; 
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
    background-size: cover;
  }
  
  .header-container{
      width: 92%;
      margin: 80px auto 0 auto;
  }
  
  .logo{
      background-color: #9fcb00;
      height: 350px;
  }
  </code></pre>
  
  <p>I added this to the HTML: 
  <code>&lt;link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css"&gt;</code></p>