帮忙翻译一段话（关于css），大至的意思是看懂了，但翻译出来不通顺~
This property sets the background image to scroll or not to scroll with its associated element's content. The default value is scroll, which sets the background to scroll with the associated content, typically text. The alternate value, fixed, is intended to make the background static with associated content such as text scrolls on top. This property is often used to create a watermark effect similar to the proprietary attribute, bgproperties, of the <body> tag introduced by Microsoft.
[498 byte] By [msdn] at [2007-8-14 18:01:11] 