Postbird

A Postbox-style theme for Betterbird — pure userChrome / userContent CSS. No add-ons, no JS.

Quick start

git clone https://github.com/Ocanamat/Postbird.git postbird
cd postbird
./scripts/deploy.ps1        # auto-detects your profile; applies CSS + prefs + layout

deploy.ps1 does everything a fresh install needs: it copies the CSS, writes the recommended prefs (user.js — enables user stylesheets, Cards view, the Postbox-like vertical layout) and, if Betterbird is closed, the recommended layout (xulstore.json — toolbar, folder modes, compact header). Then restart Betterbird.

Re-run deploy.ps1 and restart after any change. Opt out of the extras with -SkipPrefs / -SkipLayout; -ProfilePath overrides auto-detection; -Link junctions the folder for live editing.

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Postbird recreates the look and feel of the discontinued Postbox email client — specifically its "Monterail Dark" theme: a light content area with an orange accent and a dark charcoal folder pane.

Targets Betterbird 140.x ESR (140.12.0esr-bb24). Betterbird 140 uses an HTML thread tree, so selectors are written fresh against that DOM.

What it themes

Thread pane · folder pane · unified toolbar · tabs · message header · composer · status bar — plus the email body (via userContent.css). Highlights:

• Two-line "card" message rows, warm-neutral text, pale-blue unread dots, a per-account colour band, a solid-orange selection, centred sender avatars.
• Dark charcoal folder pane with account-coloured icons and orange unread pills.
• Two-tone toolbar with flat, functionally-coloured action icons.
• Reader and composer show the message as a floating white card on a grey frame (consistent read/compose look).
• Plain-text email readability (line-width cap, pre wrap, muted quotes).

Requirements

• Betterbird 140.x (toolkit.legacyUserProfileCustomizations.stylesheets = true).
• Thread pane in Cards view.
• Optional: the Auto Profile Picture add-on for sender gravatars (Postbird sizes/centres them if present; it doesn't require them).

Deploying (scripts/deploy.ps1)

One command does a full install: it copies the CSS into your profile, writes the recommended prefs, and (when Betterbird is closed) the recommended layout. Run it again — and restart Betterbird — after any change; the loaders are only read at startup.

./scripts/deploy.ps1                        # full install into the auto-detected profile
./scripts/deploy.ps1 -SkipPrefs -SkipLayout # CSS only — don't touch prefs/layout
./scripts/deploy.ps1 -Link                  # live-edit mode (junction, no re-copy)
./scripts/deploy.ps1 -ProfilePath 'C:\...\xxxx.default-release'

Option	What it does
(none)	Auto-detect the profile (profiles.ini default, else newest *.default-release under %APPDATA%\Betterbird or …\Thunderbird), then run all three steps below.
-ProfilePath <dir>	Use this profile directory instead of auto-detecting — for non-standard setups or a second profile.
-SkipPrefs	Skip step 2: don't write the recommended prefs (user.js).
-SkipLayout	Skip step 3: don't write the recommended layout (xulstore.json).
-Link	Junction chrome/postbird into the profile instead of copying, so repo edits are live (the loaders are still copied; a restart is still needed).

The three steps:

1. CSS — copies userChrome.css, userContent.css and chrome/postbird/ into <profile>\chrome\.
2. Prefs → configure-prefs.ps1 writes a managed block to user.js (enables user stylesheets, Cards view, the Postbox-like vertical layout, icon-over-text toolbar, threaded view). These are re-applied every startup; run configure-prefs.ps1 -Remove to unlock them for editing in the UI.
3. Layout → configure-xulstore.ps1 writes xulstore.json (unified toolbar, Unified Folders + All + Tags, auto-hide menu bar, compact header). Betterbird must be closed for this — it rewrites that file on exit — so if the app is running, deploy.ps1 skips this step with a note. These are live settings you can still change afterwards in the UI.

Steps 2 and 3 can also be run on their own (both auto-detect the profile the same way). After deploying, restart Betterbird.

Configure

All colours and sizes are --pb-* tokens in chrome/postbird/config.css — edit there, redeploy, restart. Components reference tokens only.

chrome/
  userChrome.css              loader (UI shell)
  userContent.css             loader (email body)
  postbird/
    config.css                ALL design tokens (single source of truth)
    components/*.css            one file per UI region
    content/message-body.css    email body styling
docs/                          selector map, migration runbook, smoke test, backlog
scripts/deploy.ps1

Design goal: cheap repair

Betterbird ESR updates move selectors. Postbird is built so a break is findable in minutes: every rule maps to a row in docs/selector-map.md, and docs/migration-runbook.md is the step-by-step fix. See CONTRIBUTING.md for the full working agreement.

Development

• main — the published branch (default). Releases tagged here.
• feat/<name> — one branch per feature/fix off main, merged via PR.

Roadmap (post-v1.0)

These are future directions, not commitments; several would mean moving beyond the current CSS-only approach (a userChrome theme can't show a settings UI or import files on its own — that needs a real add-on).

• userChrome.js behaviour layer — via a userChromeJS loader, add things CSS can't (each needs DOM reparenting/toggling): a quick-reply box above the message body, an account-name pill in the header, moving the star/flag next to the subject, and collapsible message headers.
• Package as a Thunderbird/Betterbird add-on (MailExtension / theme).
• Import external palettes — map Postbox colour themes (and formats like ColorSublime / themes.vscode.one) onto config.css tokens.
• In-app settings page to switch themes and enable/disable postbird.
• Per-mod toggles (à la Obsidian Style Settings): enable/disable each mod, with custom colours / sizes / fonts.
• Add-on-specific mods with the same enable/disable + customisation.
• Breaking-change checklist / detector for Betterbird updates.

Credits

• Postbox and its Monterail Dark theme — the interface this recreates (design inspiration; no Postbox code or assets are redistributed here).
• Betterbird and Mozilla Thunderbird — the client and upstream this themes.
• Prior-art community userChrome projects that informed the techniques here: aris-t2/customcssfortb, rafaelmardojai/thunderbird-gnome-theme, and other Betterbird/Thunderbird userChrome themes shared by the community.
• Auto Profile Picture add-on — sender gravatars in the message list.

Licence

MIT. Postbird's CSS/docs/scripts only; it targets — but bundles none of — Betterbird/Thunderbird/Mozilla (MPL-2.0) or Postbox. See NOTICE for the full scope statement.