css - Page resizing and reshaping when scroll bar shows -

I have a small problem in building my website.

Everything is working fine, except that if the content of a page is too high on the site, and the page is long, this way you can access the entire page through the browser's scroll bar All the pages on the page need to be scrolled to read, the page changes itself / resets differently, and it will not have the same status as other pages, whose content is captured and any scrolling do not require.

I am using HTML5 dtd, and I am using this CSS for the hole page:

    
 Where  
  #container {margin: 0 pixels; Padding: 0 pixels; } #wrapper {text-align: left; Margin: 0 px auto; Padding: 0 pixels; Width: 900 pixels; }   
 What could be wrong, I really do not know what I am doing, because the entire page in the site places itself on a site with less content.  
 Here's the full code on JSN:.   
 
 
 Add a style element so that it will always show the scroll bar:  
  Overflow-y: scroll;   
 In this way the content will not restore itself, because there will be no difference in the small content and the larger.  
 To run the ball for Mozilla Firefox, you may need to add:  
  overflow: -moz-scrollbar-vertical;   
 Although that tip was done a year ago, Firefox can improve itself since then, try it.