Firefox 69 will stop parsing userContent.css and userChrome.css by default
Mozilla developers have decided to disable by default processing of the userContent.css and userChrome.css files, which allow the user to override the design of sites or the Firefox interface. The reason for disabling the default is to reduce browser startup time. Changing behavior via userContent.css and userChrome.css is done extremely rarely by users, and loading CSS data consumes additional resources (optimization removes unnecessary calls [β¦]