title: What is this css error?
body: <pre><code>XUL box for div element contained an inline br child, forcing all its children to be wrapped in a block.
  </code></pre>
  
  <p>It is just an alert but not a fatal error, the webpage won't have any problems with this error, but it took place in my firebug console which is annoying, how to prevent this? Or how to ignore these errors in firebug?</p>
  
  <p>I suspect it is cause by this :</p>
  
  <pre><code>#top_icon01{
      position:relative;
      background-image : url('../hill_header/img/top_Icon_i01.png');
      background-repeat : no-repeat;
      background-size : 56px 56px;
      background-position: 50% 20px;
      width : 172px;
      height : 130px;
      padding-top : 25px;
      text-align: center;
      display:block;
      display:-webkit-box;
      display:-moz-box;
      -webkit-box-pack:center;
      -webkit-box-align:center;
      -moz-box-pack:center;
      -moz-box-align:center;
  }
  </code></pre>
  
  <p>I provide some more details:
  I <strong>didn't tick show chrome error</strong>, see this is very annoying.
  <img src="https://i.stack.imgur.com/0Mryg.png" alt="enter image description here">
         If I remove  the top header   :</p>
  
  <pre><code>&lt;div id='topHeader'&gt;
      &lt;section id='top_middle_panel'&gt;
          &lt;div id='top_ryan'&gt;
          &lt;span class='float'&gt; 
              &lt;div id='top_icon01' class='top_icons'&gt; 
                  &lt;h1&gt;Design&lt;/h1&gt;&lt;br&gt;&lt;h6&gt;Create Value&lt;/h6&gt;
              &lt;/div&gt;
          &lt;/span&gt;
          &lt;span class='float'&gt; 
              &lt;div id='top_icon02' class='top_icons'&gt; 
                  &lt;h1&gt;Multimedia&lt;/h1&gt;&lt;br&gt;&lt;h6&gt;Amazing Presentation&lt;/h6&gt;
              &lt;/div&gt;
          &lt;/span&gt;
          &lt;span class='float'&gt; 
              &lt;div id='top_icon03' class='top_icons'&gt; 
                  &lt;h1&gt;Marketing&lt;/h1&gt;&lt;br&gt;&lt;h6&gt;Connect to The World&lt;/h6&gt;
              &lt;/div&gt;
          &lt;/span&gt;
          &lt;/div&gt;
      &lt;/section&gt;
  &lt;/div&gt;  
  </code></pre>
  
  <p>There is <strong>no more errors.</strong></p>