title: Make a line of divs with borders and margins fill the width dynamically
body: <p>Consider the following code:</p>
  
  <p><strong>CSS:</strong></p>
  
  <pre class="lang-css prettyprint-override"><code>.output {
      margin-right:10px;
      border:1px solid #000;
  }
  .box{
      border-right:1px solid #000;
  }
  .first{
      border-left:1px solid #000;
  }
  </code></pre>
  
  <p><strong>HTML:</strong></p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;div class="line"&gt;
      &lt;div class="output"&gt;5&lt;/div&gt;
      &lt;div class="boxes"&gt;
          &lt;div class="box first"&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;/div&gt;
          &lt;div class="box"&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;/div&gt;
          &lt;div class="box"&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;/div&gt;
          &lt;div class="box"&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;/div&gt;
          &lt;div class="box last"&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;/div&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>I want the divs to horizontally line up and fill the 'line' div' (the space of the parent), but dynamically e.g. I do not want to specify fixed widths for each of the boxes I just want them to fill up the horizontal space.</p>
  
  <p>Can this be done?</p>