title: Make a legend fill up the full width within the fieldset
body: <p>I would like to have a background for a <code>legend</code> field within a <code>fieldset</code>. And I want it to take up the full width, but only within the fieldset. If I use <code>legend {width: 100%}</code> it will be <strong>wider</strong> than the <code>fieldset</code>.</p>
  
  <p>Here is an example, runnable in <a href="http://jsfiddle.net/jonas_io/TAvRF/" rel="noreferrer">JSFiddle</a>:</p>
  
  <pre><code>&lt;html&gt;
  &lt;head&gt;
  &lt;style&gt;
  fieldset {
      border:0;
      outline: 1px solid gray;
  }
  
  legend {
      font-weight:bold;
      background: orange;
      width: 100%
  }
  &lt;/style&gt;
  &lt;/head&gt;
  &lt;body&gt;
  &lt;fieldset&gt;
      &lt;legend&gt;Legend&lt;/legend&gt;
      Content of Fieldset
  &lt;/fieldset&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>Is there any way I can make the <code>legend</code> only fill up the width within the <code>fieldset</code>?</p>