Windows Dark Mode Doesn't Apply to PDFs
You enabled Windows dark mode, every app went dark — and then a PDF opened blinding white. That is not a bug. Windows dark mode controls app UI, not the colors baked into a document.
Why Windows dark mode skips PDFs
Windows dark mode tells apps to use a dark UI scheme. A PDF is not a UI element — it is a document with its own embedded colors. When Microsoft Edge or any other viewer opens a PDF, it renders the page background exactly as the file was authored, and the OS theme has no authority over the colors inside the PDF.
Why Edge and Acrobat "contrast" modes are not enough
Edge's "Increase contrast" PDF setting and Adobe Acrobat's accessibility colors are display filters applied inside that one app. They turn backgrounds grey rather than truly dark, can mangle the colors in diagrams and charts, and disappear the moment you open the file in another viewer.
The correct fix: convert the PDF itself
Rewriting the color operators inside the PDF content streams produces a file that stays dark in the Edge, Chrome, and Firefox built-in viewers, in Acrobat, and in mobile readers. DimlyPDF's dark mode converter does this for free in your browser using MuPDF WebAssembly — no install, no upload, and the text layer stays fully selectable and searchable.
One caveat: pure scanned PDFs are images, so DimlyPDF adds a dark background frame but cannot invert the scanned paper itself.