Index: js/lightbox.js
===================================================================
--- js/lightbox.js	(revision 34)
+++ js/lightbox.js	(working copy)
@@ -662,7 +662,7 @@
       var lightboxTop = (Lightbox.topPosition == '' ? (arrayPageSize[3] / 10) : Lightbox.topPosition) * 1;
       pageHeight = pageHeight + arrayPageScroll[1] + lightboxTop;
     }
-    $('#overlay').css({'height': pageHeight + 'px', 'width': arrayPageSize[0] + 'px'});
+    $('#overlay').css({'height': pageHeight + 'px', 'width': '100%'});
 
     // Gecko browsers (e.g. Firefox, SeaMonkey, etc) don't handle pdfs as
     // expected.