title: How to make a navigation bar like this in Bootstrap?
body: <p><a href="http://riotdesign.eu/en/" rel="nofollow">http://riotdesign.eu/en/</a></p>
  
  <p>first it seems to be a default
  then it changes to fixed-top
  and there's an animation effect in between, seems to be done in CSS</p>
  
  <p>my logic is using javascript to detect the window scroll bar's offset and toggle the navbar class attribute. Can it be done in this way?</p>
  
  <p>I took a look at the original page's code, didn't get nothing cuz it's too messy. And the page is pretty laggy in my browser. I figure their solution may not be wise. So I came here. :)</p>
  
  <p>Correct me if I'm wrong.</p>