ie6, ie7, ie8 perfectly support position:fixed ultimate solution_Experience exchange

.fixed{
position:fixed; / *For other browsers such as Firefox,*/
Top: 700px;/*Ibid 同 同*/
Width: 30px;
Height: 30px;
Cursor: Pointer;
Display: none;
}
.ie{ _position: absolute;
_clear: both;
_top:expression(eval(document.compatMode &&
document.compatMode=='CSS1Compat' )                                                                                documentElement                                                                                                                                           . .clientHeight-this.clientHeight) - 1); }