position-fixed.css

/*Make position:fixed work in IE6!*/

.fixed-top    /* position fixed Top    */{position:fixed;bottom:auto;top:0;}
.fixed-bottom /* position fixed Bottom */{position:fixed;bottom:0;top:auto;}
.fixed-left   /* position fixed Left   */{position:fixed;right:auto;left:0;}
.fixed-right  /* position fixed right  */{position:fixed;right:0;left:auto;}

* html,* html body   /* IE6 Fixed Position Jitter Fix */{background-image:url(about:blank);background-attachment:fixed;}
* html .fixed-top    /* IE6 position fixed Top        */{position:absolute;bottom:auto;top:expression(eval(document.documentElement.scrollTop));}
* html .fixed-right  /* IE6 position fixed right      */{position:absolute;right:auto;left:expression(eval(document.documentElement.scrollLeft+document.documentElement.clientWidth-this.offsetWidth)-(parseInt(this.currentStyle.marginLeft,10)||0)-(parseInt(this.currentStyle.marginRight,10)||0));}
* html .fixed-bottom /* IE6 position fixed Bottom     */{position:absolute;bottom:auto;top:expression(eval(document.documentElement.scrollTop+document.documentElement.clientHeight-this.offsetHeight-(parseInt(this.currentStyle.marginTop,10)||0)-(parseInt(this.currentStyle.marginBottom,10)||0)));}
* html .fixed-left   /* IE6 position fixed Left       */{position:absolute;right:auto;left:expression(eval(document.documentElement.scrollLeft));}

/* 原文链接：http://subtlegradient.com/articles/2009/07/29/css_position_fixed_for_ie6.html */