title: Why negative right margin not work?
body: <p>Since the edge of an element with <code>margin-left: -10px</code> crosses the edge of its parent, why doesn’t the same happen with <code>margin-right: -10px</code>?</p>
  
  <p><a href="http://jsfiddle.net/c9ZHr/1/" rel="noreferrer">example</a></p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>div {
    background: red;
    width: 200px;
    height: 100px;
  }
  
  p {
    background: blue;
    width: 100%;
  }
  
  .left {
    margin-left: -10px;
  }
  
  .right {
    margin-right: -10px;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div&gt;
    &lt;p class="left"&gt;Hello&lt;/p&gt;
  &lt;/div&gt;
  &lt;div&gt;
    &lt;p class="right"&gt;Hello&lt;/p&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>