Fix Firefox layout 'moving' trouble

Hi everyone !
I've used for a short period and I found that Punbb has a small trouble with firefox.
The trouble is when you move from a short page to a long page, the webpage will move a little when the Firefox vertical scrollbar appears. I've googled and found 2 ways to fix it.

1: add this to stylename.css
html, body{
    height: 100%;
    margin-bottom: 1px;
    }

OR

2: add this to stylename.css
html, body{
    height: 100%;
    overflow-y:scroll;
    }

These code will force scrollbar appear, and you wont see anything moves.

Hope this usefull