title: get height of div from masterpage
body: <p>How can I get the height of a <code>div</code> which is placed inside a masterpage?</p>
  
  <p>I'm able to set the height as follow:</p>
  
  <pre><code>((HtmlControl)this.Master.FindControl("sidebar")).Style.Add("height", "600px");
  </code></pre>
  
  <p>Now I'm trying to get the height from my <code>div</code> called <code>mainPage</code>, how can I do this?</p>