title: IE10 developer tool cause style missing
body: <p>I have a page1 including page2 with "iframe" tag,both of these two pages link to the same stylesheet,everything works fine,until i press "F12" to toggle developer tool in IE10,some of the classes miss styles defined in the css file suddenly,and the two pages go into a wrong display. Can anyone help?</p>
  
  <p>there are two methods to solve this problem, change the class name or add a timestamp after style url. Why?</p>