simplify logic for finding slide backgrounds

js/reveal.js

@@ -3869,25 +3869,12 @@
 	 */
 	function getSlideBackground( x, y ) {
 
-		// When printing to PDF the slide backgrounds are nested
-		// inside of the slides
-		if( isPrintingPDF() ) {
-			var slide = getSlide( x, y );
-			if( slide ) {
-				return slide.slideBackgroundElement;
-			}
-
-			return undefined;
-		}
-
-		var horizontalBackground = dom.wrapper.querySelectorAll( '.backgrounds>.slide-background' )[ x ];
-		var verticalBackgrounds = horizontalBackground && horizontalBackground.querySelectorAll( '.slide-background' );
-
-		if( verticalBackgrounds && verticalBackgrounds.length && typeof y === 'number' ) {
-			return verticalBackgrounds ? verticalBackgrounds[ y ] : undefined;
+		var slide = getSlide( x, y );
+		if( slide ) {
+			return slide.slideBackgroundElement;
 		}
 
-		return horizontalBackground;
+		return undefined;
 
 	}