diff --git a/app/src/main/java/app/grapheneos/pdfviewer/PdfViewer.java b/app/src/main/java/app/grapheneos/pdfviewer/PdfViewer.java
index 936f70851..c1c505439 100644
--- a/app/src/main/java/app/grapheneos/pdfviewer/PdfViewer.java
+++ b/app/src/main/java/app/grapheneos/pdfviewer/PdfViewer.java
@@ -130,6 +130,7 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
     private String mEncryptedDocumentPassword;
     private List<CharSequence> mDocumentProperties;
     private InputStream mInputStream;
+    private boolean invertedMode = false;
 
     private PdfviewerBinding binding;
     private TextView mTextView;
@@ -416,8 +417,17 @@ public void onPageFinished(WebView view, String url) {
                 mDocumentState = STATE_LOADED;
                 invalidateOptionsMenu();
                 loadPdfWithPassword(mEncryptedDocumentPassword);
+
+                if (invertedMode) injectDarkThemeCss(view);
+            }
+            private void injectDarkThemeCss(WebView view) {
+                String js = "javascript:(function() {" +
+                        "document.body.style.filter = 'invert(1) hue-rotate(180deg)';" +
+                        "})()";
+                view.evaluateJavascript(js, null);
             }
 
+
             @Override
             public boolean onRenderProcessGone(WebView view, RenderProcessGoneDetail detail) {
                 if (detail.didCrash()) {
@@ -730,7 +740,7 @@ public boolean onPrepareOptionsMenu(@NonNull Menu menu) {
                 R.id.action_next, R.id.action_previous, R.id.action_first, R.id.action_last,
                 R.id.action_rotate_clockwise, R.id.action_rotate_counterclockwise,
                 R.id.action_view_document_properties, R.id.action_share, R.id.action_save_as,
-                R.id.action_outline));
+                R.id.action_toggle_inverted_mode, R.id.action_outline));
         if (BuildConfig.DEBUG) {
             ids.add(R.id.debug_action_toggle_text_layer_visibility);
             ids.add(R.id.debug_action_crash_webview);
@@ -759,6 +769,7 @@ public boolean onPrepareOptionsMenu(@NonNull Menu menu) {
         enableDisableMenuItem(menu.findItem(R.id.action_next), mPage < mNumPages);
         enableDisableMenuItem(menu.findItem(R.id.action_previous), mPage > 1);
         enableDisableMenuItem(menu.findItem(R.id.action_save_as), mUri != null);
+        enableDisableMenuItem(menu.findItem(R.id.action_toggle_inverted_mode), mUri != null);
         enableDisableMenuItem(menu.findItem(R.id.action_view_document_properties),
                 mDocumentProperties != null);
 
@@ -821,6 +832,9 @@ public boolean onOptionsItemSelected(MenuItem item) {
             return true;
         } else if (itemId == R.id.action_save_as) {
             saveDocument();
+        }else if (itemId == R.id.action_toggle_inverted_mode) {
+            invertedMode = !invertedMode;
+            loadPdf();
         } else if (itemId == R.id.debug_action_toggle_text_layer_visibility) {
             binding.webview.evaluateJavascript("toggleTextLayerVisibility()", null);
             return true;
diff --git a/app/src/main/res/menu/pdf_viewer.xml b/app/src/main/res/menu/pdf_viewer.xml
index 16cd9b289..37d3f342d 100644
--- a/app/src/main/res/menu/pdf_viewer.xml
+++ b/app/src/main/res/menu/pdf_viewer.xml
@@ -72,6 +72,12 @@
         android:icon="@drawable/ic_outline_bulletlist_24dp"
         android:title="@string/action_outline" />
 
+    <item
+        android:id="@+id/action_toggle_inverted_mode"
+        android:icon="@drawable/ic_outline_bulletlist_24dp"
+        android:title="@string/action_toggle_inverted_mode" />
+
+
     <item
         android:id="@+id/action_view_document_properties"
         android:title="@string/action_view_document_properties"
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index ef05b47df..b61cf8a87 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -13,6 +13,7 @@
     <string name="action_share">Share</string>
     <string name="action_save_as">Save as</string>
     <string name="action_outline">Outline</string>
+    <string name="action_toggle_inverted_mode">Toggle inverted mode</string>
     <string name="action_view_document_properties">Properties</string>
     <string name="action_close">Close</string>