Hide pdf.js extra canvas element

Author: mrtcode

pdfjs/viewer.css

@@ -24,6 +24,16 @@ body {
 	transform: rotate(270deg) translateX(-100%);
 }
 
+#hiddenCopyElement,
+.hiddenCanvasElement {
+	position: absolute;
+	top: 0;
+	left: 0;
+	width: 0;
+	height: 0;
+	display: none;
+}
+
 .pdfViewer {
 	/* Define this variable here and not in :root to avoid to reflow all the UI
 	   when scaling (see #15929). */