From Dark and Darker Wiki
I just had this problem on Firefox and I had to close out of Firefox completely (not just the tab) and reopen it. It was either completely refreshing it or updating Firefox that fixed the issue. I would completely close out of all instances of your browser, ensure no browser related processes are running in the task manager, then reopen a new instance of the browser and see if that fixes it. Ensure your browser is up to date. If none of that works you can try restarting your PC. As a last resort try using a different browser.