diff --git a/Sources/ContentView.swift b/Sources/ContentView.swift
index dbbf15f57461..8ff416373c82 100644
--- a/Sources/ContentView.swift
+++ b/Sources/ContentView.swift
@@ -2055,6 +2055,30 @@ struct ContentView: View {
         return -max(0, min(titlebarPadding, hostingSafeAreaTop))
     }
 
+    nonisolated static func customTitlebarLeadingPadding(
+        isFullScreen: Bool,
+        isSidebarVisible: Bool,
+        sidebarWidth: CGFloat,
+        minimumSidebarWidth: CGFloat,
+        titlebarLeadingInset: CGFloat
+    ) -> CGFloat {
+        if isFullScreen && !isSidebarVisible {
+            return 8
+        }
+
+        let minimumSidebarTitleInset = max(titlebarLeadingInset, minimumSidebarWidth + 12)
+        guard isSidebarVisible else {
+            return minimumSidebarTitleInset
+        }
+
+        let visibleSidebarTitleInset = sidebarWidth + 12
+        // Absorb floating-point drift around the minimum-width clamp.
+        guard sidebarWidth > minimumSidebarWidth + 0.5 else {
+            return minimumSidebarTitleInset
+        }
+        return max(titlebarLeadingInset, visibleSidebarTitleInset)
+    }
+
     private func terminalContent(appearance: WindowAppearanceSnapshot) -> some View {
         let mountedWorkspaceIdSet = Set(mountedWorkspaceIds)
         let mountedWorkspaces = tabManager.tabs.filter { mountedWorkspaceIdSet.contains($0.id) }
@@ -2334,6 +2358,13 @@ struct ContentView: View {
 
     private func customTitlebar(appearance: WindowAppearanceSnapshot) -> some View {
         let titlebarContentHeight = max(1, WindowChromeMetrics.appTitlebarHeight - 2)
+        let leadingPadding = Self.customTitlebarLeadingPadding(
+            isFullScreen: isFullScreen,
+            isSidebarVisible: sidebarState.isVisible,
+            sidebarWidth: sidebarWidth,
+            minimumSidebarWidth: minimumSidebarWidth,
+            titlebarLeadingInset: titlebarLeadingInset
+        )
         return ZStack {
             // Enable window dragging from the titlebar strip without making the entire content
             // view draggable (which breaks drag gestures like tab reordering).
@@ -2365,7 +2396,7 @@ struct ContentView: View {
             }
             .frame(height: titlebarContentHeight)
             .padding(.top, 2)
-            .padding(.leading, (isFullScreen && !sidebarState.isVisible) ? 8 : (sidebarState.isVisible ? sidebarWidth + 12 : titlebarLeadingInset))
+            .padding(.leading, leadingPadding)
             .padding(.trailing, 8)
         }
         .frame(height: WindowChromeMetrics.appTitlebarHeight)
diff --git a/cmuxTests/WindowAndDragTests.swift b/cmuxTests/WindowAndDragTests.swift
index 626b64658077..929eb6cecb81 100644
--- a/cmuxTests/WindowAndDragTests.swift
+++ b/cmuxTests/WindowAndDragTests.swift
@@ -3,6 +3,7 @@ import AppKit
 import Carbon.HIToolbox
 import Darwin
 import PDFKit
+import Testing
 import SwiftUI
 import UniformTypeIdentifiers
 import WebKit
@@ -1958,6 +1959,73 @@ final class TitlebarLeadingInsetPassthroughViewTests: XCTestCase {
 }
 
 
+@Suite("Custom titlebar leading padding")
+struct CustomTitlebarLeadingPaddingTests {
+    @Test func hiddenSidebarUsesMinimumSidebarTitleInset() {
+        #expect(
+            ContentView.customTitlebarLeadingPadding(
+                isFullScreen: false,
+                isSidebarVisible: false,
+                sidebarWidth: 216,
+                minimumSidebarWidth: 216,
+                titlebarLeadingInset: 82
+            ) == 228
+        )
+    }
+
+    @Test func minimumWidthVisibleSidebarMatchesHiddenSidebarTitleInset() {
+        let hidden = ContentView.customTitlebarLeadingPadding(
+            isFullScreen: false,
+            isSidebarVisible: false,
+            sidebarWidth: 216,
+            minimumSidebarWidth: 216,
+            titlebarLeadingInset: 82
+        )
+        let visible = ContentView.customTitlebarLeadingPadding(
+            isFullScreen: false,
+            isSidebarVisible: true,
+            sidebarWidth: 216,
+            minimumSidebarWidth: 216,
+            titlebarLeadingInset: 82
+        )
+
+        #expect(visible == hidden)
+    }
+
+    @Test func widerSidebarPushesTitlebarContentRight() {
+        let hidden = ContentView.customTitlebarLeadingPadding(
+            isFullScreen: false,
+            isSidebarVisible: false,
+            sidebarWidth: 216,
+            minimumSidebarWidth: 216,
+            titlebarLeadingInset: 82
+        )
+        let visible = ContentView.customTitlebarLeadingPadding(
+            isFullScreen: false,
+            isSidebarVisible: true,
+            sidebarWidth: 320,
+            minimumSidebarWidth: 216,
+            titlebarLeadingInset: 82
+        )
+
+        #expect(visible > hidden)
+        #expect(visible == 332)
+    }
+
+    @Test func fullscreenHiddenSidebarKeepsCompactInset() {
+        #expect(
+            ContentView.customTitlebarLeadingPadding(
+                isFullScreen: true,
+                isSidebarVisible: false,
+                sidebarWidth: 216,
+                minimumSidebarWidth: 216,
+                titlebarLeadingInset: 82
+            ) == 8
+        )
+    }
+}
+
+
 @MainActor
 final class FolderWindowMoveSuppressionTests: XCTestCase {
     private func makeWindow() -> NSWindow {