Did you ever had the problem viewing webpages without scrollbars in firefox?
example of webpage on local machine viewed in firefox: website johec

Here is the style sheet structure how to fix firefox with sidebars for your html page.
The body tag gives the browser a 100% view in height and margin of 0px.

html{
overflow: -moz-scrollbars-vertical;
height:100%;
}

body{
height:100%;
margin-left: 0px;
margin-top: 0px;
margin-right: 0px;
margin-bottom: 0px;
}