How to get the CSS rules compatible with a node?

It's possible to know what CSS rules is applied to a specific node?

Example:

<div class="test-node">
   <strong>Test</strong>
 </div>
 

And the CSS rules:

div           { color: blue }
 div:hover     { color: green; }
 .test-node    { font-weight: bold; }
 
 div > strong  { color: red; }
 

So, the div node is affected by two rules div and .test-node and the div:hover if hover node only. The strong node is affected by div and div:hover rule, because it is inner a div, but the color property is overwrited by your own rule div > strong (example http://jsfiddle.net/yyf9v/).

Basically I need discovery how I can do the samething that Chrome Inspector does in javascript. If you use Chrome, go to Inspector (CTRL + Shift + J, Elements and select a node). You will se a Styles tab, that show element.style rule (attribute style basically) and the Matched CSS Rules... I need this!

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