title: How to align element to right side of div box?
body: <h1>How to align element to right side of div box?</h1>
  
  <h3>My div</h3>
  
  <pre><code>&lt;div id="foo"&gt;
      &lt;div id="tree"&gt;Some Text here&lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <h3>My css</h3>
  
  <pre><code>#foo {
      display: block;
      width: 500px;
      height: 500px;
      background: #5e5e5e;
  }
  
  #tree {
      width: 100px;
      height: 30px;
      background: #000000;
  }
  </code></pre>
  
  <p>I need <strong>tree</strong> placed at top-right side of <strong>foo</strong>.</p>