1. Reset  page floating margins as 0px for html body, div, iframe tags
html 
{
overflow: auto;
}

html, body, div, iframe 
{
 margin: 0px; 
 padding: 0px; 
 height: 100%; 
 border: none;
}

2. Transform iframe Tag behavior in CSS.
iframe 
{
 display: block; 
 width: 100%; 
 border: none; 
 overflow-y: auto; 
 overflow-x: hidden;
}

3. Setting iframe properties for resolve cross browser issues.

<iframe id=”tree” name=”tree” src=”http://www.w3lessons.com/&#8221; frameborder=”0″ marginheight=”0″ marginwidth=”0″ width=”100%” height=”100%” scrolling=”auto”>

Sumber : www.w3lessons.com/2011/12/create-full-screen-iframe-or-full.html