title: How can I get a popup to be a relative size?
body: <p>I want external links to open in a new window in a process that is obvious to the user so want the popup window to be a relative size to the parent window.  Initially I just used the target attribute but then started using something like this: </p>
  
  <pre><code>&lt;a href="http://example.org"  
  onclick="window.open(this.href,'window','width=810,height=480,location=0, resizable, scrollbars, toolbar=0, menubar=0') ;return false;"&gt;example.org&lt;/a&gt;
  </code></pre>
  
  <p>But I can only get this to work with pixel values, and I want to make the popup's width and height relative to the devices screen size (%).
  Seems simple enough, but I can't find anything online that simply explains how to do it.
  Can anyone help?
  Thanks in advance.</p>
  
  <p><strong>EDIT</strong>
  This is a boilerplate page:</p>
  
  <pre><code>&lt;?php 
  require("docHead.php"); 
  ?&gt; this includes everything needed at the head of a document
  &lt;title&gt;...&lt;/title&gt; varies with the page
  &lt;/head&gt; 
  &lt;body&gt;
  &lt;?php 
  require("bannerMenu.php"); 
  ?&gt; navigation etc
  &lt;div id=".."&gt;
    &lt;div id=".."&gt;
          &lt;h1&gt;...&lt;/h1&gt;
          &lt;h2&gt;...&lt;/h2&gt; 
          Ipsum lorem etc &lt;a href=.....&gt;
          &lt;?php
          require("footer.php"); 
          ?&gt;
    &lt;/div&gt;
  &lt;/div&gt;
  &lt;/body&gt;    
  &lt;/html&gt;
  </code></pre>