diff --git a/web/pdf_viewer.css b/web/pdf_viewer.css
index 56322b72a..bbd6ca97b 100644
--- a/web/pdf_viewer.css
+++ b/web/pdf_viewer.css
@@ -155,6 +155,7 @@
 
 .pdfViewer .page canvas {
   margin: 0;
+  display: block;
 }
 
 .pdfViewer .page canvas .structTree {