Firefox Quantum

Quick theme that may match Adapta-Nokto, get this

https://addons.mozilla.org/en-US/firefox/addon/native-dark/
Disable shadow? https://github.com/spikespaz/firefox-nativedark/issues/29

Set ‘Static color’ to 29353B and the rest to

To get some curves on tabs and various other hacks, in your profile folder add chrome/userChrome.css.

Or be evil and switch to Chrome, obviously with smoothscroll extension
https://chrome.google.com/webstore/detail/smoothscroll/nbokbjkabcmbfdlbddjidfmibcpneigj/related