{
  pkgs,
  lib,
  stdenv,
  specialArgs,
  ...
}: let
  extensions = with specialArgs.ff-addons; [
    bitwarden
    darkreader
    i-dont-care-about-cookies
    privacy-badger
    ublock-origin
    tree-style-tab
    tridactyl
  ];

  customChrome = ''
    @-moz-document url(chrome://browser/content/browser.xhtml) {
      /* tabs on bottom of window */
      /* requires that you set
       * toolkit.legacyUserProfileCustomizations.stylesheets = true
       * in about:config
       */
      #main-window body { flex-direction: column-reverse !important; }
      #navigator-toolbox { flex-direction: column-reverse !important; }
      #urlbar {
        top: unset !important;
        bottom: calc((var(--urlbar-toolbar-height) - var(--urlbar-height)) / 2) !important;
        box-shadow: none !important;
        display: flex !important;
        flex-direction: column !important;
      }
      #urlbar-input-container {
        order: 2;
      }
      #urlbar > .urlbarView {
        order: 1;
        border-bottom: 1px solid #666;
      }
      #urlbar-results {
        display: flex;
        flex-direction: column-reverse;
      }
      .search-one-offs { display: none !important; }
      .tab-background { border-top: none !important; }
      #navigator-toolbox::after { border: none; }
      #TabsToolbar .tabbrowser-arrowscrollbox,
      #tabbrowser-tabs, .tab-stack { min-height: 28px !important; }
      .tabbrowser-tab { font-size: 80%; }
      .tab-content { padding: 0 5px; }
      .tab-close-button .toolbarbutton-icon { width: 12px !important; height: 12px !important; }
      toolbox[inFullscreen=true] { display: none; }
    }
  '';

  userChrome = customChrome;

  # ~/.mozilla/firefox/PROFILE_NAME/prefs.js | user.js
  settings = {
    "app.normandy.first_run" = false;
    "app.shield.optoutstudies.enabled" = false;

    # disable updates (pretty pointless with nix)
    "app.update.channel" = "default";

    "browser.contentblocking.category" = "standard"; # "strict"
    "browser.ctrlTab.recentlyUsedOrder" = false;

    "browser.download.viewableInternally.typeWasRegistered.svg" = true;
    "browser.download.viewableInternally.typeWasRegistered.webp" = true;
    "browser.download.viewableInternally.typeWasRegistered.xml" = true;

    "browser.search.region" = "DE";

    "browser.shell.checkDefaultBrowser" = false;
    "browser.tabs.loadInBackground" = true;
    "browser.urlbar.placeholderName" = "EnteEnteLauf";
    "browser.urlbar.showSearchSuggestionsFirst" = false;

    # disable all the annoying quick actions
    "browser.urlbar.quickactions.enabled" = false;
    "browser.urlbar.quickactions.showPrefs" = false;
    "browser.urlbar.shortcuts.quickactions" = false;
    "browser.urlbar.suggest.quickactions" = false;

    "distribution.searchplugins.defaultLocale" = "en-US";

    "doh-rollout.balrog-migration-done" = true;
    "doh-rollout.doneFirstRun" = true;

    "general.useragent.locale" = "en-US";

    "extensions.activeThemeID" = "firefox-compact-dark@mozilla.org";

    "extensions.extensions.activeThemeID" = "firefox-compact-dark@mozilla.org";
    "extensions.update.enabled" = false;
    "extensions.webcompat.enable_picture_in_picture_overrides" = true;
    "extensions.webcompat.enable_shims" = true;
    "extensions.webcompat.perform_injections" = true;
    "extensions.webcompat.perform_ua_overrides" = true;

    "privacy.donottrackheader.enabled" = true;
    "browser.translations.enable" = false;

    # Yubikey
    "security.webauth.u2f" = true;
    "security.webauth.webauthn" = true;
    "security.webauth.webauthn_enable_softtoken" = false;
    "security.webauth.webauthn_enable_usbtoken" = true;

    "toolkit.legacyUserProfileCustomizations.stylesheets" = true;
    "layout.word_select.stop_at_punctuation" = false;
  };
in {
  programs.firefox = {
    enable = true;

    package = pkgs.firefox-bin;

    profiles = {
      default = {
        isDefault = true;
        id = 0;
        inherit extensions settings userChrome;
      };
    };
  };
}