Firefox suport

Firefox newly implements custom formatters. This release should enable it thanks to work of Sebastian Zartner.

What's Changed

• Added support and info for custom formatters in Firefox by @SebastianZ in #72
• Adjusted styling to work with Firefox by @SebastianZ in #73
• Fixed formatting for Firefox by @SebastianZ in #74

New Contributors

• @SebastianZ made their first contribution in #72

Full Changelog: v1.0.6...v1.0.7