$(document).ready(function() {
   // put all your jQuery goodness in here.
	var myDate=new Date()
  var hour=myDate.getHours()
  if ( (hour>7) && (hour<20) )
  {
			$("body").removeClass("night");
			$("body").addClass("day");
  }else{
			$("body").addClass("night");
			$("body").removeClass("day");
  }//end of if
   
});