limit size of media elements when printing to pdf

js/reveal.js

@@ -461,6 +461,9 @@
 		// Let the browser know what page size we want to print
 		injectStyleSheet( '@page{size:'+ pageWidth +'px '+ pageHeight +'px; margin: 0;}' );
 
+		// Limit the size of certain elements to the dimensions of the slide
+		injectStyleSheet( '.reveal img, .reveal video, .reveal iframe{max-width: '+ slideWidth +'px; max-height:'+ slideHeight +'px}' );
+
 		document.body.classList.add( 'print-pdf' );
 		document.body.style.width = pageWidth + 'px';
 		document.body.style.height = pageHeight + 'px';