//// CONFIGURATION VARIABLES:

var name    = "#sidebar";
var menu_top_limit   = 0;
var menu_top_margin  = 0;
var menu_shift_duration = 500;
var menuYloc = null;
///////////////////////////////////

$(window).scroll(function() 
{ 
 // Calculate the top offset, adding a limit
 offset = menuYloc + $(document).scrollTop() + menu_top_margin;

 // Limit the offset to 241 pixels...
 // This keeps the menu out of our header area:
 if(offset < menu_top_limit)
  offset = menu_top_limit;

 // Give it the PX for pixels:
 offset += "px";

 // Animate:
 $(name).animate({top:offset},{duration:menu_shift_duration,queue:false});
 });