PDF Dark Mode Style Settings Option

src/scss/Info/styleSettingsConfig.scss

@@ -3326,6 +3326,12 @@ settings:
         description: This option removes the title from pinned tabs and adds back the default file icon for the markdown files. Helps reduce the horizontal space wasted by pinned tabs. You can still see the title when you hover over the icon. NOTE - This option requires Installer Version 1.1.9+ due to use of CSS `has()`. Also, might not work on certain Mobile clients.
         default: false
         type: class-toggle
+    -
+        id: pt-pdf-dark-theme
+        title: Enable PDF Dark Theme
+        description: This option adds styling to the PDF pages by blending in with the colour scheme in Dark mode; making it more eye friendly. This isn't a perfect solution. Note that some images might look inverted and colours be a different shade compared to the original file.
+        default: false
+        type: class-toggle
     -
         id: theme-info
         title: Theme Info

src/scss/Plugins/Core/PDFViewer.scss

@@ -115,4 +115,12 @@
 	box-shadow: unset;
 	opacity: 0.4;
 }
+
+// https://mwichary.medium.com/dark-theme-in-a-day-3518dde2955a
+.pt-pdf-dark-theme.theme-dark {
+	.pdf-viewer .canvasWrapper,
+	.pdf-sidebar-container img.thumbnailImage {
+		filter: invert(1) hue-rotate(180deg) saturate(100%);
+		mix-blend-mode: screen;
+	}
 }