4.0.1rc1

4.0.1rc1: 2026-08-23

Note

Nightly notice: This is a pre-release tracking Mastodon main. It is the first release after the 4.0.0 stable rewrite and collects the fixes made since.
💀 Compatibility: Mastodon 4.8.0-alpha.1, built from mastodon/main.

For Mastodon 4.6.0 stable / 4.7.0, use 4.0.0.

Mostly navigation and modal fixes, plus one upstream break that made the More icon disappear.

What changed

The More icon came back

Mastodon made the id prop optional on its Icon component (#40211), so the icon class is only emitted when an id is present. The More menu passes an empty id, which used to render an empty icon- class that Bird UI keyed its replacement on. That class is gone, so the background image no longer applied while the path stayed hidden, leaving an empty space next to the word. Bird UI now selects that icon by its element instead of by an id upstream can drop again.

Media modal footer (#195)

The footer under an opened image was using core's oversized 24px buttons spread with a rounded rectangle hover, which looked nothing like the rest of the UI.

• Icons down to 18px with a readable counter beside them, matching the status action bar.
• Buttons spread across the media instead of bunching at one edge.
• Round hover behind the icon, the same shape regular posts use, in place of core's rounded rectangle.
• Boost glyph rendered in white over media, with the core path underneath hidden so only one icon shows.
• Modal overlay narrowed from 600px to 500px so the bar tracks the media.
• Dropped core's drop shadow behind icons over media.

Navigation

• Lists no longer overlap the trends section on short viewports (#193).
• Column-link hover pills are no longer clipped on their inline-start edge on large screens.
• The compact navigation font size on screens below 1080px height is no longer overridden by the desktop rule.
• The mobile navigation bar sits above the slideout pane, so the hamburger menu is not covered, and mobile navigation links are padded away from the edge.
• The left navigation scrolls, so items below Bookmarks stay reachable at high browser zoom.

Profile

• Account badges have spacing between them, so a Muted or Blocked notice is no longer flush against a role badge.

Install script

• Other installed themes (like Tangerine) are preserved instead of themes.yml being rebuilt from scratch.

Impact by install method

Custom CSS users (paste CSS into Mastodon admin)

The compiled dist/mastodon-bird-ui.css ships updated. Re-paste it into Mastodon admin Custom CSS.

Mastodon admins running install-to-mastodon.sh

git pull the Bird UI clone, re-run the install script, and recompile assets. No themes.yml changes since 4.0.0.

Heads up for mementomori-social/mastodon fork users

The star/heart choice is now kept when you open a picture. That one is a fork-side change, not Bird UI: the media footer hardcoded the star icons and never read the preference. Pull the fork branch and recompile: https://github.com/mementomori-social/mastodon/tree/mementomods-2026-08-23

Changelog

• Redesign the media modal footer to match the status action bar (#195)
• Add spacing between account badges so Muted is not flush against them
• Fix lists overlapping the trends section on short viewports (#193)
• Fix the More icon missing from the navigation panel
• Fix the column-link hover pill being clipped on its inline-start edge on large screens by restoring overflow visible on the navigation pane, where the scroll fix was never needed
• Fix the compact navigation font size (17px) on screens below 1080px height being overridden by the 18px desktop rule
• Keep the mobile navigation bar above the slideout pane so the hamburger menu is no longer covered
• Pad the mobile navigation links so their labels are not tight against the edge
• Make the left navigation scroll so items below Bookmarks (Settings, More) stay reachable at high browser zoom, including extreme zoom on low-resolution screens with the accessible themes
• Preserve other installed themes (like Tangerine) when installing Bird UI instead of rebuilding themes.yml from scratch
• Fix the reply post indicator sticking to the left edge in non-thread replies (mastodon/mastodon#39554)
• Reset the status prepend padding only in reply threads, where Mastodon 4.7.0-alpha.1 adds a thread margin (mastodon/mastodon#39521)