diff --git a/src/vpu-pdf-preview.js b/src/vpu-pdf-preview.js
index 501833d098ddf0bb6499edefcd22644adbc442e1..90932341f125651978ca7c3d335a07f539f967b3 100644
--- a/src/vpu-pdf-preview.js
+++ b/src/vpu-pdf-preview.js
@@ -184,6 +184,10 @@ export class PdfPreview extends ScopedElementsMixin(VPULitElement) {
                 align-items: center;
                 justify-content: center;
             }
+
+            canvas {
+                border: solid 1px black;
+            }
         `;
     }