This is at least a partial credits-file of people that have contributed to the 'Firefox-UI-Fix' project.
    It is sorted by name.
        The fields are: name (N), email (E), web-address(W), Copyright(C), license(L).
    Thanks,

                 black7375
----------
    Major Contributors

N: AveYo
E: aveyo@yahoo.com
W: https://github.com/AveYo

N: Jan Janssen
E: medhefgo@web.de
W: https://github.com/medhefgo

N: Yunsup Sim
E: pedogunu@gmail.com
W: https://ethansup.net

----------
    Contributors

N: 7k5x
E: 7k5xlp0onfire@gmail.com
W: https://github.com/7k5x

N: Ajith-stark
E: ajith.kum.12342@gmail.com
W: https://github.com/Ajith-stark

N: Andmagdo
W: https://github.com/andmagdo

N: anzz1
W: https://github.com/anzz1

N: Backseat-Driver
W: https://www.reddit.com/user/Backseat-Driver/

N: badprogramshere
W: https://github.com/badprogramshere

N: BPower0036
W: https://github.com/BPower0036

N: Burak Yigit Kaya
E: ben@byk.im
W: https://byk.im/

N: dr460nf1r3
E: njcrypted@protonmail.com
W: https://dr460nf1r3.me/

N: Filip Š
E: filip.stamcar@hotmail.com
W: https://www.filips.si/

N: hellojaccc
E: kim@taekyeong.me
W: https://github.com/hellojaccc

N: James Upjohn
E: jammehcow@jammehcow.co.nz
W: https://github.com/jammehcow

N: Jonta
W: https://github.com/Jonta

N: mamen
W: https://www.mamen.at

N: MarNicGit
W: https://github.com/MarNicGit

N: ph3b3
E: phoebeleong8@gmail.com
W: https://phoebe-leong.github.io/

N: Rahul Ramkumar
E: rahulram226@gmail.com
W: https://rahulramkumar.dev

N: Roel
E: Nyubis@gmail.com
W: https://github.com/Nyubis

N: SanderTheDragon
E: sanderthedragon@zoho.com
W: https://gitlab.com/SanderTheDragon

N: sean z
E: ean@vsxd.com
W: https://vsxd.com/

N: Sylvain
E: B00ze64@hotmail.com
W: https://github.com/B00ze64

N: Tatsuyuki Ishi
E: ishitatsuyuki@gmail.com
W: https://github.com/ishitatsuyuki

----------
    Reference Projects & Resources

N: Compact Mode Firefox Css
W: https://github.com/Godiesc/compactmodefirefoxcss
C: Copyright (c) 2021 Godiesc
L: MPL 2.0

N: EdgeFox
W: https://github.com/23Bluemaster23/EdgeFox
C: Copyright (c) 2021 23Bluemaster23
L: Unspecified License (Copyright holder approved)

N: EdgeTabSeparater.userChrome.css
W: https://gist.github.com/mmis1000/08d8de4bbe70c04423f0b966bcc286b1
C: Copyright (c) 2021 Mmis1000 <mmis10002@gmail.com>
L: MIT

N: Feather
W: https://github.com/feathericons/feather
C: Copyright (c) 2013-2017 Cole Bemis
L: MIT

N: firefox-csshacks
W: https://github.com/MrOtherGuy/firefox-csshacks
C: Copyright (c) 2018 MrOtherGuy
L: MPL 2.0

N: Fluent UI System Icons
W: https://github.com/microsoft/fluentui-system-icons
C: Copyright (c) 2020 Microsoft Corporation
L: MIT

N: gecko-dev
W: https://hg.mozilla.org/mozilla-central/
C: Copyright (c) 1998–2021 The Mozilla Foundation
L: MPL 2.0

N: MaterialFox
W: https://github.com/muckSponge/MaterialFox
C: Copyright (c) 2018 muckSponge
L: MIT

N: Multi-Account-Containers
W: https://github.com/mozilla/multi-account-containers
C: Copyright (c) 1998–2021 The Mozilla Foundation
L: MPL 2.0

N: plyr
W: https://github.com/sampotts/plyr
C: Copyright (c) 2017 Sam Potts
L: MIT

N: PS-Menu
W: https://github.com/chrisseroka/ps-menu
C: Copyright (c) 2016 chrisseroka
L: MIT

N: Quantum Nox Firefox Dark Full Theme
W: https://github.com/Izheil/Quantum-Nox-Firefox-Dark-Full-Theme
C: Copyright (c) 2017 Izheil
L: MPL 2.0

N: quietfox
W: https://github.com/coekuss/quietfox
C: Copyright (c) 2019 coekuss
L: MIT

N: ShadowFox
W: https://github.com/overdodactyl/ShadowFox
C: Copyright (c) 2017 overdodactyl
L: MIT

N: SVG Repo
E: info@svgrepo.com
W: https://www.svgrepo.com
C: Copyright (c) 2017 svgrepo.com
L: CC0

N: uc.css.js
W: https://github.com/aminomancer/uc.css.js
C: Copyright (c) 2019 aminomancer
L: CC BY-NC-SA 4.0

N: userChrome.csshacks
W: https://gist.github.com/DCzajkowski/baaf7bc81aae5278d690eaae951a823b
C: Copyright (c) 2021 Dariusz Czajkowski
L: CC0

N: userChrome.css
W: https://gist.github.com/Dragoner7/ec2319e5038a6b4722d3e692713f9471
C: Copyright (c) 2021 Dragoner7
L: MPL 2.0

N: userChrome.org
W: https://www.userchrome.org/what-is-userchrome-css.html
C: Copyright (c) 2021 Jefferson Scher
L: CC BY 4.0

N: Waterfox
W: https://github.com/WaterfoxCo/Waterfox
C: Copyright (c) 2012 Waterfox Limited
L: MPL 2.0