[css-backgrounds-4] typo. fixes #117

Author: tabatkins

css-backgrounds-4/Overview.bs

@@ -73,7 +73,7 @@ Background Positioning: the 'background-position' shorthand property</h3>
 			then the shorthand sets
 			'background-position-inline' and 'background-position-block' to the specified values.
 			Otherwise
-			the shorthand sets 
+			the shorthand sets
 			'background-position-x' and 'background-position-y' to the specified values.
 
 			Issue: Specify the value assignment in more detail. Should expand just like Level 3.
@@ -92,7 +92,7 @@ Background Positioning Longhands: the 'background-position-x', 'background-posit
 		Initial: left
 		Applies to: all
 		Inherited: no
-		Percentages: refer to width of background positioning area <em>minus</em> height of background image
+		Percentages: refer to width of background positioning area <em>minus</em> width of background image
 		Media: visual
 		Computed value: A list, each item consisting of: an offset given as a combination of an absolute length and a percentage, plus an origin keyword
 	</pre>