diff --git a/CHANGELOG.md b/CHANGELOG.md
index 08960b23..739658c2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,22 @@ All notable changes to tty7 are documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Fixed
+
+- **The macOS traffic lights sit on the same line as the tiles beside them.**
+  The buttons AppKit draws are 14 points tall and gpui hangs the top of the
+  frame `y` points below the window's top edge, so the lights' centre falls
+  seven points under the bar's top; the New Tab and sidebar tiles are centred
+  in the bar's content box instead — its height less the hairline `TitleBar`
+  draws along the bottom edge. The position was still the one the 40-point bar
+  called for, carried over by hand when the bar grew to 48 without that
+  hairline in it, which left the lights half a point below everything else in
+  the row: one device pixel on a Retina panel. `traffic_light_position()` now
+  derives it from `TITLE_BAR_HEIGHT`, and a test holds the lights to the tile
+  line through the next change of bar height.
+
 ## [26.9.4] - 2026-09-29
 
 ### Added
diff --git a/src/ui/theme.rs b/src/ui/theme.rs
index 1652df26..04bfb375 100644
--- a/src/ui/theme.rs
+++ b/src/ui/theme.rs
@@ -11,14 +11,33 @@ use crate::terminal::view::{
     ClearScrollback, CopyText, CutText, FindInTerminal, FindNext, FindPrevious, PasteText,
     RedoEdit, SelectAll, UndoEdit,
 };
+use crate::ui::app::TITLE_BAR_HEIGHT;
 use crate::ui::i18n::{L10nKey, t};
 use crate::ui::presets;
 use crate::ui::presets::Fill;
 #[cfg(target_os = "windows")]
 use std::sync::OnceLock;
 
+/// Where macOS puts the window's traffic lights over the tab strip: nine
+/// points in from the left edge, and centred on the row of chrome tiles they
+/// share the bar with.
+///
+/// `y` is the gap between the window's top edge and the *top* of the button
+/// frame, and macOS draws those buttons 14 points tall — so the lights' centre
+/// falls seven points below it. The tiles sit in the middle of the bar's
+/// content box instead, which is `TITLE_BAR_HEIGHT` less the hairline
+/// `TitleBar` draws along its bottom edge. Deriving the number from those two
+/// facts rather than writing it out is what keeps the lights on the tile line:
+/// the value the 40-point bar needed was rewritten by hand when the bar grew
+/// to 48, without the border in it, and left the lights half a point — one
+/// device pixel on a Retina panel — below everything beside them.
 pub(crate) fn traffic_light_position() -> Point<Pixels> {
-    point(px(9.), px(17.))
+    // AppKit's own button frame, and the border `TitleBar` adds to the bar it
+    // wraps. Neither moves with the bar's height.
+    const BUTTON_H: f32 = 14.;
+    const BAR_BORDER: f32 = 1.;
+
+    point(px(9.), px((TITLE_BAR_HEIGHT - BAR_BORDER - BUTTON_H) / 2.))
 }
 
 pub(crate) fn set_menus(cx: &mut App) {
@@ -1022,6 +1041,18 @@ mod tests {
     use super::*;
     use gpui::TestAppContext;
 
+    /// The lights share a line with the chrome tiles they sit beside. gpui
+    /// hangs the top of the 14pt frame `y` below the window's top edge, so
+    /// their centre is seven points under that; the tiles are centred in the
+    /// bar's content box, its height less the hairline `TitleBar` draws along
+    /// the bottom. Sixteen and a half points today, out of the 48pt bar.
+    #[test]
+    fn the_traffic_lights_sit_on_the_chrome_rows_centre() {
+        let position = traffic_light_position();
+        assert_eq!(position.x, px(9.));
+        assert_eq!(position.y + px(7.), px((TITLE_BAR_HEIGHT - 1.) / 2.));
+    }
+
     #[gpui::test]
     fn effective_preset_follows_the_cached_system_appearance(cx: &mut TestAppContext) {
         cx.update(|cx| {