解决代码：

_position: absolute;  _top: expression(documentElement.scrollTop + 150 + "px");

 

完整代码：

kefu{width: 131px; position: fixed; right: 5px;  top: 150px; color: #252d69; background: #fff; _position: absolute;  _top: expression(documentElement.scrollTop + 150 + "px"); }