Move web controls position as a group

I'd like to find a efficient way to move programatically a group of web controls (declared at desing time).

 

I can do it for the visible property.

Panel1.Controls.Add(btnCalendar0);

Panel1.Controls.Add(btnCalendar1);

Panel1.Visible = false;

 

It doesn't work for moving them around. Don't know why, the following code make them dissapear.

Panel1.Style["left"] = "100px";

...