I use Firefox locally to review the HTML/CSS while creating web pages (Win7 & Win10). Upon browser update, Firefox stopped displaying mask of any image format (SVG or PNG). I did solve this issue in 2020 by changing the settings. about:config > privacy.file_unique_origin changing: to 'false' > refresh tab. Yet, since October 2021, it's no longer helping. After a browser update, I don't see the images with a mask, see attachment. The mask images show OK when the HTML page is on the server, but codding requires a constant 'quick check,' and usually uploading to the server is a final step. Can anyone help? I prepared a simple example page [[https://artenergy.com/mask]] with a download link. Thus one can open this file locally to see the issue. Thank you!