Firefox Focus enable the Tracking Protection feature inside the browser preferences manually. Users can also view types of trackers on a page by tapping on the shield icon next to the URL bar. A panel will pop-up and shows what kind of trackers are on that page: ad trackers, analytics trackers, social trackers or content trackers. Firefox Focus can be set as content-blocker in the Safari web browser options. After activating the Safari integration in the Firefox Focus settings, it will disable trackers automatically in the background when browsing using the Safari browser. Pressing the trash icon while browsing will delete all
Quirks mode Web Consortium, which maintains the XHTML specification, suggests that authors of XHTML documents could consider omitting the XML declaration. Henri Sivonen compiled a list of various document types and how they are treated in the most common browsers, showing whether pages are rendered in Quirks, Standards, or Almost standards mode. The criterion used for "Almost standards mode" is non-standard table cell height rendering. This table applies to content served with the Content-Type text/html. Content served with the Content-Type application/xhtml+xml is rendered in Standards mode in Chrome, Firefox, Internet Explorer 9, Safari, and Opera. Internet Explorer 6, 7, and 8 do