title: jQuery slide changes the width when slides
body: <p>The code works fine.
  <a href="http://jsfiddle.net/vyWTL/3/" rel="nofollow">jsFiddle</a></p>
  
  <p>The only problem is that it changes its width when slides (when press "click here"). Seems like it cuts the width that corresponds to 100px of the margin-left in #slider.</p>
  
  <p>Why does it "jump" and how to fix it? Is there anything wrong with the code?</p>
  
  <p>What is in there: a slider of the centered div that has a content and a sticky footer.</p>