background-blur = macos-glass-regular works opposite to what is expected

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Issue Description

Thank you very much for the awesome work you've done with Ghostty. I really like version 1.3, but I found an issue that I'd like to report.
I tried to use the new background-blur = macos-glass-regular configuration, but I noticed that the blur works opposite to what is expected: the Ghostty window is less transparent when the window is active and more transparent when the window is inactive.
This behavior is the opposite of that of every other app (and Ghostty itself with the other background-blur options), so I think it's a bug.
Edit: I’ve updated the screenshots to non-HDR versions.

Expected Behavior

Ghostty should be more transparent when the window is active and less transparent when the window is inactive.
As a reference, this is the stock macOS terminal (and the expected behaviour):

• macOS Terminal - active window (more transparent):

---

• macOS Terminal - inactive window (less transparent):

Actual Behavior

As of version 1.3 (and with the config background-blur = macos-glass-regular enabled), Ghostty is less transparent when the window is active and more transparent when the window is inactive.

• Ghostty - active window (less transparent):

---

• Ghostty - inactive window (more transparent):

Reproduction Steps

1. Open Ghostty
2. Add background-blur = macos-glass-regular to the config file
3. Look at the background blur of the active Ghostty window and compare it to the inactive Ghostty window

Ghostty Logs

sudo log stream --level debug --predicate 'subsystem=="com.mitchellh.ghostty"'
Filtering the log data using "subsystem == "com.mitchellh.ghostty""
Timestamp                       Thread     Type        Activity             PID    TTL
2026-03-12 22:57:09.346725+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:default] ghostty version=1.3.0
2026-03-12 22:57:09.347169+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:default] ghostty build optimize=ReleaseFast
2026-03-12 22:57:09.347182+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:default] runtime=.none
2026-03-12 22:57:09.347189+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:default] font_backend=.coretext
2026-03-12 22:57:09.347194+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:default] renderer=renderer.generic.Renderer(renderer.Metal)
2026-03-12 22:57:09.347201+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:default] libxev default backend=kqueue
2026-03-12 22:57:09.351089+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:os_locale] os_locale: detected system locale=en_IT.UTF-8
2026-03-12 22:57:09.351168+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:os_locale] os_locale: setlocale after unset lang result=C
2026-03-12 22:57:09.351176+0100 0xfbab     Error       0x0                  2100   0    ghostty: [com.mitchellh.ghostty:os_locale] os_locale: setlocale failed with LANG and system default. Falling back to en_US.UTF-8
2026-03-12 22:57:09.351250+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:os_locale] os_locale: setlocale default result=en_US.UTF-8
2026-03-12 22:57:09.352325+0100 0xfbb0     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:sentry] sentry: sentry envelope does not contain crash, discarding
2026-03-12 22:57:09.418941+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:default] reading configuration file path=/Users/user/Library/Application Support/com.mitchellh.ghostty/config
2026-03-12 22:57:09.419019+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:default] reading configuration file path=/Users/user/Library/Application Support/com.mitchellh.ghostty/config
2026-03-12 22:57:09.419044+0100 0xfbab     Error       0x0                  2100   0    ghostty: [com.mitchellh.ghostty:config] config: both config files `/Users/user/Library/Application Support/com.mitchellh.ghostty/config` and `/Users/user/Library/Application Support/com.mitchellh.ghostty/config` exist.
2026-03-12 22:57:09.419049+0100 0xfbab     Error       0x0                  2100   0    ghostty: [com.mitchellh.ghostty:config] config: loading them both in that order
2026-03-12 22:57:09.419180+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:config] config: default shell src=passwd value=/usr/local/bin/fish
2026-03-12 22:57:09.419188+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:config] config: default working directory src=passwd value=/Users/user
2026-03-12 22:57:09.525091+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:ghostty] config reload notification
2026-03-12 22:57:09.525262+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:config] config: default shell src=passwd value=/usr/local/bin/fish
2026-03-12 22:57:09.525270+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:config] config: default working directory src=passwd value=/Users/user
2026-03-12 22:57:09.525300+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:ghostty] config change notification
2026-03-12 22:57:09.543154+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:ghostty] known but unimplemented action action=40
2026-03-12 22:57:09.549058+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:io_exec] io_exec: found Ghostty resources dir: /Applications/Ghostty.app/Contents/Resources/ghostty
2026-03-12 22:57:09.549127+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:io_exec] io_exec: shell integration automatically injected shell=.fish
2026-03-12 22:57:09.549202+0100 0xfbab     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:ghostty] known but unimplemented action action=22
2026-03-12 22:57:09.551050+0100 0xfbc6     Info        0x0                  2100   0    ghostty: [com.mitchellh.ghostty:io_exec] io_exec: started subcommand path=/usr/bin/login pid=2101
2026-03-12 22:57:13.142953+0100 0xfbab     Debug       0x0                  2100   0    ghostty: [com.mitchellh.ghostty:AppDelegate] application will save window state

Ghostty Version

Ghostty 1.3.0

Version
  - version: 1.3.0
  - channel: stable
Build Config
  - Zig version   : 0.15.2
  - build mode    : .ReleaseFast
  - app runtime   : .none
  - font engine   : .coretext
  - renderer      : renderer.generic.Renderer(renderer.Metal)
  - libxev        : kqueue

OS Version Information

macOS 26.3

(Linux only) Display Server

None

(Linux only) Desktop Environment/Window Manager

No response

Minimal Ghostty Configuration

background-blur = macos-glass-regular

Additional Relevant Configuration

background-opacity = 0.95
# Same background opacity as the macOS Terminal profile used in the screenshots

I acknowledge that:

• I have reviewed the FAQ and confirm that my issue is NOT among them.
• I have searched the Ghostty repository (both open and closed Discussions and Issues) and confirm this is not a duplicate of an existing issue or discussion.
• I have checked the "Preview" tab on all text fields to ensure that everything looks right, and have wrapped all configuration and code in code blocks with a group of three backticks (```) on separate lines.