Increase specificity of PDF.js canvas style (#7219)

GitOrigin-RevId: 62e4424b5e5681bcbf1d377394f6bd8587a34ea6

services/web/frontend/stylesheets/app/editor/pdf.less

@@ -201,7 +201,7 @@
     .full-size;
     background-color: @pdfjs-bg;
     overflow: scroll;
-    canvas,
+    .canvasWrapper > canvas,
     div.pdf-canvas {
       background: white;
       box-shadow: @pdf-page-shadow-color 0px 0px 10px;