css-fixed兼容写法

解决IE6中fixed闪动问题(效果稍微好一点，不能完全解决闪动问题)

*{background-image:url(about:blank);background-attachment:fixed;}

body{

    background-image:url(about:blank);background-attachment:fixed;

    background-color: #fff;

}

右侧距顶部45px固定

#boxC{

    position: fixed;

    z-index: 999;

    top: 45px;

    right: 0;

    _position:absolute;

    _top:expression(documentElement.scrollTop + 45);

    overflow:hidden; 

    *zoom:1;

}

底部固定

#boxA{

    position: fixed;

    z-index: 999;

    bottom: 0px;

    left: 0px;

    _position:absolute;

    _top:expression(documentElement.scrollTop + documentElement.clientHeight-this.offsetHeight);

    overflow:hidden; 

    *zoom:1;

}