diff --git a/gulpfile.js b/gulpfile.js
index a25dd399c..71bd903a4 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -192,8 +192,6 @@ function createWebpackConfig(
     DEFAULT_PREFERENCES: defaultPreferencesDir
       ? getDefaultPreferences(defaultPreferencesDir)
       : {},
-    DIALOG_POLYFILL_CSS:
-      defines.GENERIC && !defines.SKIP_BABEL ? getDialogPolyfillCSS() : "",
   });
   const licenseHeaderLibre = fs
     .readFileSync("./src/license_header_libre.js")
@@ -821,12 +819,6 @@ function getDefaultPreferences(dir) {
   return AppOptions.getAll(OptionKind.PREFERENCE);
 }
 
-function getDialogPolyfillCSS() {
-  return fs
-    .readFileSync("node_modules/dialog-polyfill/dist/dialog-polyfill.css")
-    .toString();
-}
-
 gulp.task("locale", function () {
   const VIEWER_LOCALE_OUTPUT = "web/locale/";
 
@@ -1585,8 +1577,6 @@ function buildLib(defines, dir) {
     DEFAULT_PREFERENCES: getDefaultPreferences(
       defines.SKIP_BABEL ? "lib/" : "lib-legacy/"
     ),
-    DIALOG_POLYFILL_CSS:
-      defines.GENERIC && !defines.SKIP_BABEL ? getDialogPolyfillCSS() : "",
   });
 
   const inputStream = merge([
diff --git a/web/overlay_manager.js b/web/overlay_manager.js
index 885066106..e4d7378e1 100644
--- a/web/overlay_manager.js
+++ b/web/overlay_manager.js
@@ -44,15 +44,6 @@ class OverlayManager {
     ) {
       const dialogPolyfill = require("dialog-polyfill/dist/dialog-polyfill.js");
       dialogPolyfill.registerDialog(dialog);
-
-      if (!this._dialogPolyfillCSS) {
-        this._dialogPolyfillCSS = true;
-
-        const style = document.createElement("style");
-        style.textContent = PDFJSDev.eval("DIALOG_POLYFILL_CSS");
-
-        document.head.prepend(style);
-      }
     }
 
     dialog.addEventListener("cancel", evt => {