how to set iframe height to 100% with javascript

how to set iframe height to 100% with javascri开发者_运维知识库pt Example : http://mkb.ma/5f

Here is the CSS for the iframe that page:

#mkbnavbar iframe#srcpage {
  height:90%;
  margin:0;
  padding:0;
  width:100%;
  z-index:10;
}

And remaining 10% is given to bar at the top.

He is actually using CSS to do this on this page:

#mkbnavbar iframe#srcpage {
height: 90%;
width:100%;
z-index: 10;
margin: 0; padding: 0;
  -webkit-box-sizing: border-box;

}