Hello Girls and guys!

Right now I'm sitting making a website, where I have my header that is 100% in width, then I have box-shadow on it using the -moz-box-shadow, -webkit-box-shadow and box-shadow.. Everything works fine in Firefox4.0, Safari, Chrome, Opera and Internet explorer (Using an image for Opera and IE), but Firefox3.6 cause a horizontal Scrollbar for me because of the box-shadow..

I'm using CSS3 for my site, and doing it backward-comp via images, but don't know how I should target "Firefox3.6 or less" only So I could use a image there etc, or using Overflow-x:hidden; so there won't be scrollbars for FF..

I can use

Code:
@-moz-document url-prefix() {
	body {
	overflow-x: hidden;
	}
}
To target Firefox, but don't know if it's "okay".. Can any maybe help.. The site I'm creating is: S&L | Hosting

I'm kinda lost right now Have tried anything.