Positioning div as pe rmouse click

i have a javascipt to find the mouse click cordinate
var tempX, tempY;
if (document.all)
{
tempX = event.clientX;
tempY = event.clientY;
}
else
{
tempX= evt.pageX+“px”;
tempY = evt.pageY+“px”;
}
hiddenfield.value= tempX;
i have a div control which needs to be positioned as per the click cordinates
basically left & right

but as i have the div set to runat server =true
so i need to set it from code behind
something like
div1.style(“left”)=hiddenfield.value;