title: What is the default margin value of <p> tag?
body: <p>I noticed that the <code>&lt;p&gt;</code> tag has a default margin value and it seems it's somehow related to its content's <code>font-size</code> value.</p>
  
  <p>Is there any reference that I can check out the detailed rules for this?</p>
  
  <p><a href="http://jsfiddle.net/z45R9/" rel="noreferrer">http://jsfiddle.net/z45R9/</a> Please take a look at my code here.</p>
  
  <p>Thanks,</p>