In the image, these are not tabs. These are firefox windows, being rendered as tabs (and as stacks) by sway.

I just switched to sway, and found that browser tabs no longer make sense. They were designed in the UI dark ages to make up for how terrible Windows XP's WM was. Now, though, sway can do tabs just as well as firefox can, and sometimes, even better. It is better to unify the management of all windows under a single WM, rather than this ad hoc mixture of the real, global WM, and a fake firefox-only (or terminal-only) WM. That way, all windows are managed with a single set of keyboard shortcuts.

I also found firefox's toolbar to be way too thick.

So, I used userChrome.css to hide the tab bar and adjust the toolbar's height:

/* Hide the tab bar. */
#TabsToolbar {
    visibility: collapse !important;
}

/* Adjust the toolbar height. */
#urlbar-container {
    --urlbar-container-height: var(--tbh) !important;
}
#urlbar {
    --urlbar-toolbar-height: var(--tbh) !important;
    --urlbar-height: var(--tbh) !important;
}
:root {
    --tbh: 26px !important; /* ToolBar Height. Adjust this one. */
    --toolbarbutton-inner-padding: calc((var(--tbh) - 16px)/2) !important;
    --toolbarbutton-outer-padding: 0px !important;
    --toolbar-start-end-padding: 0px !important;
    --urlbar-margin-inline: 0px !important;
}

Put this file at <profile root>/chrome/userChrome.css. You'll probably have to make the chrome directory. Then, in about:config, set toolkit.legacyUserProfileCustomizations.stylesheets to true, to get firefox to read userChrome.css. Oh, and don't forget to tell firefox to open new pages in new windows instead of new tabs.

I have also found it useful to map the firefox command to Super-C, so that I can make a new firefox window without needing to have some other firefox window already in focus.

I have also found it useful to keep an empty firefox window open in some unused workspace on its own, so that after I close what I didn't realise was the last open firefox window, firefox does not close entirely.

This is (another!!) one of Drew Devault's projects. Like harelang, it would be a gigantic simplification of existing software. And yes, it is written in harelang.

It was originally a test to see whether harelang could be used for OS development. (It can.)

0. An all-black LAMY Safari fountain pen filled with a mix of water, Platinum carbon black, and inkjet printer ink.
1. A blank sheet of A4, folded in half three times.
2. My passport.
3. A fully loaded Secrid card carrier.
4. A really nice rock. It has been in my pocket for a year. Don't think about it.
5. A dumb watch. (Casio W-59. Very small, light as a feather. Green LED-backlight LCD display. 50 metre water resist. Tough, within reason. Effectively infinite battery life.)
6. A beta of the PinePhone Pro, equipped with dreemurrs archlinux.
7. A USB drive containing all of my computers' boot partitions and Archiso.

Navalnyi's finest hour.

May he rise again in three days.