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PDF selected text selection not visible. CTRL+F not highlighted.

Making moves

When I view a PDF file using the default PDF viewer and when I double click, or click and drag my mouse cursor over a word, it does not highlight or select the text. I can use CTRL+A to select all text and it is selected, but the highlighted portion is not visible so I cannot see what is and what isn't selected. It literally looks the same as when no text is selected like the selection highlight box is clear or fully transparent instead of blue like it is on literally every other website.

Similarly, when I use ctrl+f and I have "highlight all" enabled, none of the matched words in the document are visibly highlighted.

I tried adding the following to my userContent.css file and there was absolutely no change. Zero.




.pdfViewer .textLayer {
opacity: 0.5 !important;

.pdfViewer .textLayer .highlight {
background-color: rgba(180, 0, 170, 1) !important;

.pdfViewer .textLayer .highlight.selected {
background-color: rgba(0, 100, 0, 1) !important;




It should visibly show the highlight of the highlighted text by default. To be clear, I am not talking about annotations. I'm talking about the basic function of the pdf viewer that is missing. Literally when you use ctrl+f it says "highlight all". So why isn't it visibly highlighted?

I also tried changing themes, closing and opening firefox. Nothing. It's been like this for quite a while but I normally just open documents in chrome instead. Personally, I don't think using a different browser is a solution when this is bare bones minimum functionality, it's not anything special.

As you can see from my screenshot, I have the text selection tool enabled. Although, aside from that, words matched when using CTRL+F are also not visibly highlighted. How do I make the selected text selection highlight opaque when viewing a PDF file?

Using firefox nightly 115.0a1 (2023-05-20) (64-bit)



Hmm, it should still work the same as earlier versions (this is the 20230521 build):


Does your Firefox show background colors on regular web pages, with the Find feature or otherwise?

If you check the Computed panel in the Inspector for one the areas that has the highlight class, what do you see there? Here's mine for comparison.