fix text selection for PDFs with marked content

Update viewer.css to match recent changes in pdfjs

Author: PalmerAL

pages/pdfViewer/viewer.css

@@ -141,14 +141,19 @@
     contain: strict;
   }
 
-  .textLayer > span {
+  .textLayer span {
     color: transparent;
     position: absolute;
     white-space: pre;
     cursor: text;
     transform-origin: top left;
   }
 
+  .textLayer span.markedContent {
+    top: 0;
+    height: 0;
+  }
+
   .annotationLayer img,
   .annotationLayer .popupAnnotation,
   .annotationLayer .popupWrapper {