Strange styling through injected stylesheets in Chrome

If someone stumbles on this as of 24-Feb-2022 because most web pages have black colored background due to color-scheme: dark right at the element by injected stylesheet, the culprit is 'Adobe Acrobat: PDF edit, convert, sign tools' - https://chrome.google.com/webstore/detail/adobe-acrobat-pdf-edit-co/efaidnbmnnnibpcajpcglclefindmkaj

Worked fine after disabling the extension.

Okay I've found the culprit! I've disabled each of my extensions one by one until the page showed correctly. It was the 'CSS Selector Tester'. I think it is a great tool that I often use but it shouldn't screw with my pages when I don't use it!

Interestingly the CSS Selector Tester does not work on the pages where I saw the styling problems. On other pages it works fine.

Just had this with the 'Save to Pocket' extension overriding rules in a print stylesheet.

Also assuming your Google 'incognito' (privacy mode) browser isn't running your extensions viewing the page 'incognito' can be a quick way to check if a browser extension is the issue.

I had the same issue with injected stylesheet, hiding social buttons from my website.

It turned out my Adblock plus was blocking Facebook and YouTube social buttons.