I'd really like this userchrome.css to work: https://github.com/xmansyx/Pro-Fox
... though it's broken at least on Nightly right now.

I think the new tabs style lends itself very well to being placed underneath the address bar; but userchrome.css just isn't documented adequately, & figuring out how to do it properly isn't really worth it for me right now. I wish someone made an extension that made it an option to click; it seems doable.

Just add this at the end of the code and you are done.. (hopefully it will work , dont have nightly)

*/
:root {
/* Appmenu: Reduce item padding */
--arrowpanel-menuitem-padding-block: 4px 8px !important;
/* Tabbar: reduce tab margin */
--tab-block-margin: 4px 3px !important;
}
/* Tab: Reduce height */
.tabbrowser-tab {
min-height: 24px !important;
}
/* URLBar: Fix vertical alignment */
#urlbar[breakout=true]:not([open="true"]) {
--urlbar-height: 20px !important;
--urlbar-toolbar-height: 24px !important;
}
/* Toolbar: Reduce spacing */
#urlbar-container {
--urlbar-container-height: 30px !important;
margin-top: 0 !important;
}
/* Reload Button: Fix vertical alignment */
#reload-button {
margin-block-start: -2px !important;
}

Getting really tired of Mozilla removing features and customization options. After updating to 89 my tabs were outright invisible except for the active one at the bottom of the window. Had to go hunting for fixes again — fortunately the update had already been out a few days so I found answers on reddit and figured out most of the other tweaks needed for my theme.

I'm not too up in arms about the changes, but I did really dislike the changes to the tabs. Very hard to tell them apart now, and the titles are awkward to read as well. Thankfully a friendly soul let us know how to fix it, at least for now. I also heard nasty rumours that silly Mozilla will remove this option in the about:config for Firefox 90! :(

To get the tabs back like they were before (or at least close enough):
browser.proton.enabled = false

Quoting: PangaeaI'm not too up in arms about the changes, but I did really dislike the changes to the tabs. Very hard to tell them apart now, and the titles are awkward to read as well. Thankfully a friendly soul let us know how to fix it, at least for now. I also heard nasty rumours that silly Mozilla will remove this option in the about:config for Firefox 90! :(

To get the tabs back like they were before (or at least close enough):
browser.proton.enabled = false

I tried this on Nightly (91.0a1) & Dev. Ed. (90.0b5). Reverts tabs on 90.0b5, but *not* on 91.0a1.
In both version, though, it brings back the icons on the main (hamburger) menu -- which I prefer.

The other day the upcoming UI 'refresh' for the Safari browser was introduced, and ...

Yeah... Can't wait (?!) for this beauty to inspire Mozilla.