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/*
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	VERSION: Drop Shadow jQuery Plugin 1.6  12-13-2007
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	REQUIRES: jquery.js (1.2.6 or later)
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	SYNTAX: $(selector).dropShadow(options);  // Creates new drop shadows
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					$(selector).redrawShadow();       // Redraws shadows on elements
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					$(selector).removeShadow();       // Removes shadows from elements
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					$(selector).shadowId();           // Returns an existing shadow's ID
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	OPTIONS:
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		left    : integer (default = 4)
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		top     : integer (default = 4)
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		blur    : integer (default = 2)
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		opacity : decimal (default = 0.5)
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		color   : string (default = "black")
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		swap    : boolean (default = false)
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	The left and top parameters specify the distance and direction, in	pixels, to
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	offset the shadow. Zero values position the shadow directly behind the element.
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	Positive values shift the shadow to the right and down, while negative values 
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	shift the shadow to the left and up.
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	The blur parameter specifies the spread, or dispersion, of the shadow. Zero 
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	produces a sharp shadow, one or two produces a normal shadow, and	three or four
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	produces a softer shadow. Higher values increase the processing load.
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	The opacity parameter	should be a decimal value, usually less than one. You can
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	use a value	higher than one in special situations, e.g. with extreme blurring. 
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	Color is specified in the usual manner, with a color name or hex value. The
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	color parameter	does not apply with transparent images.
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	The swap parameter reverses the stacking order of the original and the shadow.
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	This can be used for special effects, like an embossed or engraved look.
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	EXPLANATION:
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	This jQuery plug-in adds soft drop shadows behind page elements. It is only
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	intended for adding a few drop shadows to mostly stationary objects, like a
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	page heading, a photo, or content containers.
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	The shadows it creates are not bound to the original elements, so they won't
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	move or change size automatically if the original elements change. A window
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	resize event listener is assigned, which should re-align the shadows in many
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	cases, but if the elements otherwise move or resize you will have to handle
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	those events manually. Shadows can be redrawn with the redrawShadow() method
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	or removed with the removeShadow() method. The redrawShadow() method uses the
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	same options used to create the original shadow. If you want to change the
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	options, you should remove the shadow first and then create a new shadow.
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	The dropShadow method returns a jQuery collection of the new shadow(s). If
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	further manipulation is required, you can store it in a variable like this:
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		var myShadow = $("#myElement").dropShadow();
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	You can also read the ID of the shadow from the original element at a later
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	time. To get a shadow's ID, either read the shadowId attribute of the
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	original element or call the shadowId() method. For example:
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		var myShadowId = $("#myElement").attr("shadowId");  or
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		var myShadowId = $("#myElement").shadowId();
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	If the original element does not already have an ID assigned, a random ID will
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	be generated for the shadow. However, if the original does have an ID, the 
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	shadow's ID will be the original ID and "_dropShadow". For example, if the
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	element's ID is "myElement", the shadow's ID would be "myElement_dropShadow".
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	If you have a long piece of text and the user resizes the	window so that the
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	text wraps or unwraps, the shape of the text changes and the words are no
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	longer in the same positions. In that case, you can either preset the height
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	and width, so that it becomes a fixed box, or you can shadow each word
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	separately, like this:
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		<h1><span>Your</span> <span>Page</span> <span>Title</span></h1>
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		$("h1 span").dropShadow();
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	The dropShadow method attempts to determine whether the selected elements have
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	transparent backgrounds. If you want to shadow the content inside an element,
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	like text or a transparent image, it must not have a background-color or
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	background-image style. If the element has a solid background it will create a
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	rectangular	shadow around the outside box.
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	The shadow elements are positioned absolutely one layer below the original 
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	element, which is positioned relatively (unless it's already absolute).
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	*** All shadows have the "dropShadow" class, for selecting with CSS or jQuery.
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	ISSUES:
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		1)	Limited styling of shadowed elements by ID. Because IDs must be unique,
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				and the shadows have their own ID, styles applied by ID won't transfer
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				to the shadows. Instead, style elements by class or use inline styles.
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		2)	Sometimes shadows don't align properly. Elements may need to be wrapped
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				in container elements, margins or floats changed, etc. or you may just 
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				have to tweak the left and top offsets to get them to align. For example,
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				with draggable objects, you have to wrap them inside two divs. Make the 
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				outer div draggable and set the inner div's position to relative. Then 
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				you can create a shadow on the element inside the inner div.
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		3)	If the user changes font sizes it will throw the shadows off. Browsers 
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				do not expose an event for font size changes. The only known way to 
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				detect a user font size change is to embed an invisible text element and
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				then continuously poll for changes in size.
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		4)	Safari support is shaky, and may require even more tweaks/wrappers, etc.
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		The bottom line is that this is a gimick effect, not PFM, and if you push it
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		too hard or expect it to work in every possible situation on every browser,
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		you will be disappointed. Use it sparingly, and don't use it for anything 
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		critical. Otherwise, have fun with it!
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	AUTHOR: Larry Stevens (McLars@eyebulb.com) This work is in the public domain,
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					and it is not supported in any way. Use it at your own risk.
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*/
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(function($){
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	var dropShadowZindex = 1;  //z-index counter
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	$.fn.dropShadow = function(options)
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	{
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		// Default options
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		var opt = $.extend({
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			left: 4,
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			top: 4,
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			blur: 2,
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			opacity: .5,
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			color: "black",
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			swap: false
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			}, options);
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		var jShadows = $([]);  //empty jQuery collection
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		// Loop through original elements
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		this.not(".dropShadow").each(function()
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		{
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			var jthis = $(this);
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			var shadows = [];
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			var blur = (opt.blur <= 0) ? 0 : opt.blur;
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			var opacity = (blur == 0) ? opt.opacity : opt.opacity / (blur * 8);
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			var zOriginal = (opt.swap) ? dropShadowZindex : dropShadowZindex + 1;
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			var zShadow = (opt.swap) ? dropShadowZindex + 1 : dropShadowZindex;
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			// Create ID for shadow
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			var shadowId;
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			if (this.id) {
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				shadowId = this.id + "_dropShadow";
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			}
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			else {
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				shadowId = "ds" + (1 + Math.floor(9999 * Math.random()));
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			}
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			// Modify original element
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			$.data(this, "shadowId", shadowId); //store id in expando
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			$.data(this, "shadowOptions", options); //store options in expando
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			jthis
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				.attr("shadowId", shadowId)
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				.css("zIndex", zOriginal);
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			if (jthis.css("position") != "absolute") {
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				jthis.css({
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					position: "relative",
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					zoom: 1 //for IE layout
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				});
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			}
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			// Create first shadow layer
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			bgColor = jthis.css("backgroundColor");
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			if (bgColor == "rgba(0, 0, 0, 0)") bgColor = "transparent";  //Safari
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			if (bgColor != "transparent" || jthis.css("backgroundImage") != "none" 
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					|| this.nodeName == "SELECT" 
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					|| this.nodeName == "INPUT"
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					|| this.nodeName == "TEXTAREA") {		
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				shadows[0] = $("<div></div>")
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					.css("background", opt.color);								
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			}
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			else {
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				shadows[0] = jthis
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					.clone()
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					.removeAttr("id")
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					.removeAttr("name")
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					.removeAttr("shadowId")
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					.css("color", opt.color);
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			}
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			shadows[0]
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				.addClass("dropShadow")
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				.css({
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					height: jthis.outerHeight(),
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					left: blur,
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					opacity: opacity,
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					position: "absolute",
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					top: blur,
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					width: jthis.outerWidth(),
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					zIndex: zShadow
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				});
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			// Create other shadow layers
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			var layers = (8 * blur) + 1;
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			for (i = 1; i < layers; i++) {
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				shadows[i] = shadows[0].clone();
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			}
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			// Position layers
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			var i = 1;			
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			var j = blur;
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			while (j > 0) {
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				shadows[i].css({left: j * 2, top: 0});           //top
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				shadows[i + 1].css({left: j * 4, top: j * 2});   //right
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				shadows[i + 2].css({left: j * 2, top: j * 4});   //bottom
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				shadows[i + 3].css({left: 0, top: j * 2});       //left
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				shadows[i + 4].css({left: j * 3, top: j});       //top-right
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				shadows[i + 5].css({left: j * 3, top: j * 3});   //bottom-right
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				shadows[i + 6].css({left: j, top: j * 3});       //bottom-left
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				shadows[i + 7].css({left: j, top: j});           //top-left
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				i += 8;
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				j--;
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			}
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			// Create container
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			var divShadow = $("<div></div>")
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				.attr("id", shadowId) 
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				.addClass("dropShadow")
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				.css({
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					left: jthis.position().left + opt.left - blur,
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					marginTop: jthis.css("marginTop"),
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					marginRight: jthis.css("marginRight"),
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					marginBottom: jthis.css("marginBottom"),
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					marginLeft: jthis.css("marginLeft"),
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					position: "absolute",
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					top: jthis.position().top + opt.top - blur,
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					zIndex: zShadow
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				});
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			// Add layers to container	
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			for (i = 0; i < layers; i++) {
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				divShadow.append(shadows[i]);
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			}
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			// Add container to DOM
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			jthis.after(divShadow);
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			// Add shadow to return set
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			jShadows = jShadows.add(divShadow);
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			// Re-align shadow on window resize
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			$(window).resize(function()
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			{
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				try {
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					divShadow.css({
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						left: jthis.position().left + opt.left - blur,
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						top: jthis.position().top + opt.top - blur
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					});
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				}
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				catch(e){}
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			});
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			// Increment z-index counter
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			dropShadowZindex += 2;
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		});  //end each
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		return this.pushStack(jShadows);
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	};
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	$.fn.redrawShadow = function()
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	{
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		// Remove existing shadows
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		this.removeShadow();
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		// Draw new shadows
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		return this.each(function()
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		{
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			var shadowOptions = $.data(this, "shadowOptions");
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			$(this).dropShadow(shadowOptions);
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		});
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	};
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	$.fn.removeShadow = function()
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	{
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		return this.each(function()
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		{
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			var shadowId = $(this).shadowId();
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			$("div#" + shadowId).remove();
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		});
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	};
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	$.fn.shadowId = function()
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	{
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		return $.data(this[0], "shadowId");
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	};
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	$(function()  
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	{
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		// Suppress printing of shadows
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		var noPrint = "<style type='text/css' media='print'>";
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		noPrint += ".dropShadow{visibility:hidden;}</style>";
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		$("head").append(noPrint);
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	});
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})(jQuery);
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