diff --git a/web/app.js b/web/app.js
index f60bf0296..6f6897f54 100644
--- a/web/app.js
+++ b/web/app.js
@@ -671,14 +671,7 @@ const PDFViewerApplication = {
   },
 
   get supportsFullscreen() {
-    if (typeof PDFJSDev !== "undefined" && PDFJSDev.test("MOZCENTRAL")) {
-      return shadow(this, "supportsFullscreen", document.fullscreenEnabled);
-    }
-    return shadow(
-      this,
-      "supportsFullscreen",
-      document.fullscreenEnabled || document.webkitFullscreenEnabled
-    );
+    return shadow(this, "supportsFullscreen", document.fullscreenEnabled);
   },
 
   get supportsIntegratedFind() {
diff --git a/web/pdf_presentation_mode.js b/web/pdf_presentation_mode.js
index 937ee50f6..f94bea021 100644
--- a/web/pdf_presentation_mode.js
+++ b/web/pdf_presentation_mode.js
@@ -63,28 +63,19 @@ class PDFPresentationMode {
    * @returns {boolean} Indicating if the request was successful.
    */
   request() {
-    if (this.switchInProgress || this.active || !this.pdfViewer.pagesCount) {
+    if (
+      this.switchInProgress ||
+      this.active ||
+      !this.pdfViewer.pagesCount ||
+      !this.container.requestFullscreen
+    ) {
       return false;
     }
-    this._addFullscreenChangeListeners();
-    this._setSwitchInProgress();
-    this._notifyStateChange();
+    this.#addFullscreenChangeListeners();
+    this.#setSwitchInProgress();
+    this.#notifyStateChange();
 
-    if (typeof PDFJSDev !== "undefined" && PDFJSDev.test("MOZCENTRAL")) {
-      if (this.container.requestFullscreen) {
-        this.container.requestFullscreen();
-      } else {
-        return false;
-      }
-    } else {
-      if (this.container.requestFullscreen) {
-        this.container.requestFullscreen();
-      } else if (this.container.webkitRequestFullscreen) {
-        this.container.webkitRequestFullscreen(Element.ALLOW_KEYBOARD_INPUT);
-      } else {
-        return false;
-      }
-    }
+    this.container.requestFullscreen();
 
     this.args = {
       pageNumber: this.pdfViewer.currentPageNumber,
@@ -92,14 +83,10 @@ class PDFPresentationMode {
       scrollMode: this.pdfViewer.scrollMode,
       spreadMode: this.pdfViewer.spreadMode,
     };
-
     return true;
   }
 
-  /**
-   * @private
-   */
-  _mouseWheel(evt) {
+  #mouseWheel(evt) {
     if (!this.active) {
       return;
     }
@@ -122,13 +109,13 @@ class PDFPresentationMode {
       (this.mouseScrollDelta > 0 && delta < 0) ||
       (this.mouseScrollDelta < 0 && delta > 0)
     ) {
-      this._resetMouseScrollState();
+      this.#resetMouseScrollState();
     }
     this.mouseScrollDelta += delta;
 
     if (Math.abs(this.mouseScrollDelta) >= PAGE_SWITCH_THRESHOLD) {
       const totalDelta = this.mouseScrollDelta;
-      this._resetMouseScrollState();
+      this.#resetMouseScrollState();
       const success =
         totalDelta > 0
           ? this.pdfViewer.previousPage()
@@ -139,17 +126,7 @@ class PDFPresentationMode {
     }
   }
 
-  get isFullscreen() {
-    if (typeof PDFJSDev !== "undefined" && PDFJSDev.test("MOZCENTRAL")) {
-      return !!document.fullscreenElement;
-    }
-    return !!(document.fullscreenElement || document.webkitIsFullScreen);
-  }
-
-  /**
-   * @private
-   */
-  _notifyStateChange() {
+  #notifyStateChange() {
     let state = PresentationModeState.NORMAL;
     if (this.switchInProgress) {
       state = PresentationModeState.CHANGING;
@@ -168,37 +145,29 @@ class PDFPresentationMode {
    * This timeout is used to prevent the current page from being scrolled
    * partially, or completely, out of view when entering Presentation Mode.
    * NOTE: This issue seems limited to certain zoom levels (e.g. page-width).
-   *
-   * @private
    */
-  _setSwitchInProgress() {
+  #setSwitchInProgress() {
     if (this.switchInProgress) {
       clearTimeout(this.switchInProgress);
     }
     this.switchInProgress = setTimeout(() => {
-      this._removeFullscreenChangeListeners();
+      this.#removeFullscreenChangeListeners();
       delete this.switchInProgress;
-      this._notifyStateChange();
+      this.#notifyStateChange();
     }, DELAY_BEFORE_RESETTING_SWITCH_IN_PROGRESS);
   }
 
-  /**
-   * @private
-   */
-  _resetSwitchInProgress() {
+  #resetSwitchInProgress() {
     if (this.switchInProgress) {
       clearTimeout(this.switchInProgress);
       delete this.switchInProgress;
     }
   }
 
-  /**
-   * @private
-   */
-  _enter() {
+  #enter() {
     this.active = true;
-    this._resetSwitchInProgress();
-    this._notifyStateChange();
+    this.#resetSwitchInProgress();
+    this.#notifyStateChange();
     this.container.classList.add(ACTIVE_SELECTOR);
 
     // Ensure that the correct page is scrolled into view when entering
@@ -210,8 +179,8 @@ class PDFPresentationMode {
       this.pdfViewer.currentScaleValue = "page-fit";
     }, 0);
 
-    this._addWindowListeners();
-    this._showControls();
+    this.#addWindowListeners();
+    this.#showControls();
     this.contextMenuOpen = false;
 
     // Text selection is disabled in Presentation Mode, thus it's not possible
@@ -220,10 +189,7 @@ class PDFPresentationMode {
     window.getSelection().removeAllRanges();
   }
 
-  /**
-   * @private
-   */
-  _exit() {
+  #exit() {
     const pageNumber = this.pdfViewer.currentPageNumber;
     this.container.classList.remove(ACTIVE_SELECTOR);
 
@@ -231,8 +197,8 @@ class PDFPresentationMode {
     // Presentation Mode, by waiting until fullscreen mode is disabled.
     setTimeout(() => {
       this.active = false;
-      this._removeFullscreenChangeListeners();
-      this._notifyStateChange();
+      this.#removeFullscreenChangeListeners();
+      this.#notifyStateChange();
 
       this.pdfViewer.scrollMode = this.args.scrollMode;
       this.pdfViewer.spreadMode = this.args.spreadMode;
@@ -241,16 +207,13 @@ class PDFPresentationMode {
       this.args = null;
     }, 0);
 
-    this._removeWindowListeners();
-    this._hideControls();
-    this._resetMouseScrollState();
+    this.#removeWindowListeners();
+    this.#hideControls();
+    this.#resetMouseScrollState();
     this.contextMenuOpen = false;
   }
 
-  /**
-   * @private
-   */
-  _mouseDown(evt) {
+  #mouseDown(evt) {
     if (this.contextMenuOpen) {
       this.contextMenuOpen = false;
       evt.preventDefault();
@@ -274,17 +237,11 @@ class PDFPresentationMode {
     }
   }
 
-  /**
-   * @private
-   */
-  _contextMenu() {
+  #contextMenu() {
     this.contextMenuOpen = true;
   }
 
-  /**
-   * @private
-   */
-  _showControls() {
+  #showControls() {
     if (this.controlsTimeout) {
       clearTimeout(this.controlsTimeout);
     } else {
@@ -296,10 +253,7 @@ class PDFPresentationMode {
     }, DELAY_BEFORE_HIDING_CONTROLS);
   }
 
-  /**
-   * @private
-   */
-  _hideControls() {
+  #hideControls() {
     if (!this.controlsTimeout) {
       return;
     }
@@ -310,18 +264,13 @@ class PDFPresentationMode {
 
   /**
    * Resets the properties used for tracking mouse scrolling events.
-   *
-   * @private
    */
-  _resetMouseScrollState() {
+  #resetMouseScrollState() {
     this.mouseScrollTimeStamp = 0;
     this.mouseScrollDelta = 0;
   }
 
-  /**
-   * @private
-   */
-  _touchSwipe(evt) {
+  #touchSwipe(evt) {
     if (!this.active) {
       return;
     }
@@ -381,16 +330,13 @@ class PDFPresentationMode {
     }
   }
 
-  /**
-   * @private
-   */
-  _addWindowListeners() {
-    this.showControlsBind = this._showControls.bind(this);
-    this.mouseDownBind = this._mouseDown.bind(this);
-    this.mouseWheelBind = this._mouseWheel.bind(this);
-    this.resetMouseScrollStateBind = this._resetMouseScrollState.bind(this);
-    this.contextMenuBind = this._contextMenu.bind(this);
-    this.touchSwipeBind = this._touchSwipe.bind(this);
+  #addWindowListeners() {
+    this.showControlsBind = this.#showControls.bind(this);
+    this.mouseDownBind = this.#mouseDown.bind(this);
+    this.mouseWheelBind = this.#mouseWheel.bind(this);
+    this.resetMouseScrollStateBind = this.#resetMouseScrollState.bind(this);
+    this.contextMenuBind = this.#contextMenu.bind(this);
+    this.touchSwipeBind = this.#touchSwipe.bind(this);
 
     window.addEventListener("mousemove", this.showControlsBind);
     window.addEventListener("mousedown", this.mouseDownBind);
@@ -402,10 +348,7 @@ class PDFPresentationMode {
     window.addEventListener("touchend", this.touchSwipeBind);
   }
 
-  /**
-   * @private
-   */
-  _removeWindowListeners() {
+  #removeWindowListeners() {
     window.removeEventListener("mousemove", this.showControlsBind);
     window.removeEventListener("mousedown", this.mouseDownBind);
     window.removeEventListener("wheel", this.mouseWheelBind, {
@@ -425,44 +368,21 @@ class PDFPresentationMode {
     delete this.touchSwipeBind;
   }
 
-  /**
-   * @private
-   */
-  _fullscreenChange() {
-    if (this.isFullscreen) {
-      this._enter();
+  #fullscreenChange() {
+    if (/* isFullscreen = */ document.fullscreenElement) {
+      this.#enter();
     } else {
-      this._exit();
+      this.#exit();
     }
   }
 
-  /**
-   * @private
-   */
-  _addFullscreenChangeListeners() {
-    this.fullscreenChangeBind = this._fullscreenChange.bind(this);
-
+  #addFullscreenChangeListeners() {
+    this.fullscreenChangeBind = this.#fullscreenChange.bind(this);
     window.addEventListener("fullscreenchange", this.fullscreenChangeBind);
-    if (typeof PDFJSDev === "undefined" || !PDFJSDev.test("MOZCENTRAL")) {
-      window.addEventListener(
-        "webkitfullscreenchange",
-        this.fullscreenChangeBind
-      );
-    }
   }
 
-  /**
-   * @private
-   */
-  _removeFullscreenChangeListeners() {
+  #removeFullscreenChangeListeners() {
     window.removeEventListener("fullscreenchange", this.fullscreenChangeBind);
-    if (typeof PDFJSDev === "undefined" || !PDFJSDev.test("MOZCENTRAL")) {
-      window.removeEventListener(
-        "webkitfullscreenchange",
-        this.fullscreenChangeBind
-      );
-    }
-
     delete this.fullscreenChangeBind;
   }
 }