diff --git a/src/css.js b/src/css.js
index f2165f904..88c4ffa05 100644
--- a/src/css.js
+++ b/src/css.js
@@ -169,11 +169,23 @@ jQuery.each(["height", "width"], function( i, name ) {
 					});
 				}
 
-				if ( val < 0 || val === 0 && !jQuery.contains( elem.ownerDocument.documentElement, elem ) ) {
+				if ( val < 0 ) {
 					return elem.style[ name ] || "0px";
 				}
 
-				return val + "px";
+				if ( val === 0 ) {
+					val = curCSS( elem, name, name );
+
+					if ( val != null ) {
+						return val;
+					}
+				}
+
+				if ( val < 0 || val == null ) {
+					return elem.style[ name ];
+				}
+
+				return typeof val === "string" ? val : val + "px";
 			}
 		},
 
diff --git a/test/unit/css.js b/test/unit/css.js
index 8f24e2e34..2c2e9ed21 100644
--- a/test/unit/css.js
+++ b/test/unit/css.js
@@ -1,7 +1,7 @@
 module("css");
 
 test("css(String|Hash)", function() {
-	expect(42);
+	expect(41);
 
 	equals( jQuery('#main').css("display"), 'block', 'Check for css property "display"');
 
@@ -13,21 +13,19 @@ test("css(String|Hash)", function() {
 
 	var div = jQuery( "<div>" );
 
-	equals( div.css("width"), "0px", "Width on disconnected node." );
-	equals( div.css("height"), "0px", "Height on disconnected node." );
+	equals( div.css("width") || "auto", "auto", "Width on disconnected node." );
+	equals( div.css("height") || "auto", "auto", "Height on disconnected node." );
 
 	div.css({ width: 4, height: 4 });
 
 	equals( div.css("width"), "4px", "Width on disconnected node." );
 	equals( div.css("height"), "4px", "Height on disconnected node." );
 
-	var div2 = jQuery( "<div style='display:none;'><input type='text'/><textarea/></div>").appendTo("body");
+	var div2 = jQuery( "<div style='display:none;'><input type='text' style='height:20px;'/><textarea style='height:20px;'/><div style='height:20px;'></div></div>").appendTo("body");
 
-	equals( div2.find("input").css("width"), "0px", "Width on hidden input." );
-	equals( div2.find("input").css("height"), "0px", "Height on hidden input." );
-
-	equals( div2.find("textarea").css("width"), "0px", "Width on hidden textarea." );
-	equals( div2.find("textarea").css("height"), "0px", "Height on hidden textarea." );
+	equals( div2.find("input").css("height"), "20px", "Height on hidden input." );
+	equals( div2.find("textarea").css("height"), "20px", "Height on hidden textarea." );
+	equals( div2.find("div").css("height"), "20px", "Height on hidden textarea." );
 
 	div2.remove();