Firefox 3.0 recorded usage share of web browsers. Estimates of Firefox 3.0's global market share were generally in the range of 4–5%, and then dropped as users migrated to Firefox 3.5 and later Firefox 3.6. Partially as a result of this, between mid-December 2009 and the end of January 2010, Firefox 3.5 was the most popular browser (when counting individual browser versions), passing Internet Explorer 7. Mozilla ended support for Firefox 3 on March 30, 2010 with the release of 3.0.19. Firefox 3.0 was developed under the codename "Gran Paradiso". This, like other Firefox codenames, is the name of an actual place;
Web Components are inside a template will not be fetched until the template is stamped out. HTML Templates are supported in Google Chrome, Mozilla Firefox, Microsoft Edge, Safari, and Opera. Support for an early version of Custom Elements and Shadow DOM, known as "v0", is present in some Blink-based browsers like Google Chrome and Opera and is in Mozilla Firefox (requires a manual configuration change). The newer Custom Elements and Shadow DOM "v1" APIs are being implemented in Safari 10, Google Chrome (53.0.2785), and under development in Mozilla Firefox. Microsoft Edge did not implement Custom Elements or Shadow DOM. Backward compatibility with