PatternSkinCssCookbook Recipe: Center the page with a border

   * Set USERSTYLEURL = %PUBURLPATH%/%SYSTEMWEB%/PatternSkinCssCookbookCenterPageBorder/centerpageborder.css 

<style type="text/css" media="all"> 
#patternScreen { 
background-image:url("%PUBURLPATH%/%SYSTEMWEB%/PatternSkinCssCookbookCenterPageBorder/gradient_page.gif"); 
background-repeat:repeat-x; 
} 
#patternPageShadow { 
background-image:url("%PUBURLPATH%/%SYSTEMWEB%/PatternSkin/striped_pageshadow.gif"); 
} 
</style> 

If you don't write this overloading style in a template and use an external .css file, you need to set the image to the absolute url:

<style type="text/css" media="all"> 
    #patternScreen { 
        background-image:url("%ATTACHURLPATH%/gradient_page.gif"); 
        background-repeat:repeat-x; 
    } 
</style> 

You can always write a <style> in a topic - all current browsers support this - but the page won't validate as valid XHTML.