diff --git a/apps/desktop/src/app/layout-constants.ts b/apps/desktop/src/app/layout-constants.ts
index 3174fc790..8799a8885 100644
--- a/apps/desktop/src/app/layout-constants.ts
+++ b/apps/desktop/src/app/layout-constants.ts
@@ -12,6 +12,12 @@ export const PAGE_INSET_X = 'px-[clamp(1.25rem,4vw,4rem)]'
 // out to the gutter edges before re-applying PAGE_INSET_X.
 export const PAGE_INSET_NEG_X = '-mx-[clamp(1.25rem,4vw,4rem)]'
 
+// Readable cap for overlay "inner page" bodies (settings, command center). Wide
+// enough to breathe, tight enough that content doesn't sprawl on ultrawide
+// displays. Pair with `mx-auto w-full` to center within the pane. Literal string
+// for Tailwind's scanner (see PAGE_INSET_X note).
+export const PAGE_MAX_W = 'max-w-[75rem]'
+
 // Below this viewport width a docked sidebar leaves no room for content, so both
 // rails auto-collapse into the hover-reveal overlay. Single source of truth for
 // the responsive collapse point.
diff --git a/apps/desktop/src/app/overlays/overlay-split-layout.tsx b/apps/desktop/src/app/overlays/overlay-split-layout.tsx
index 6b95e0e48..330c6dbad 100644
--- a/apps/desktop/src/app/overlays/overlay-split-layout.tsx
+++ b/apps/desktop/src/app/overlays/overlay-split-layout.tsx
@@ -3,7 +3,7 @@ import type { ReactNode } from 'react'
 import type { IconComponent } from '@/lib/icons'
 import { cn } from '@/lib/utils'
 
-import { PAGE_INSET_X } from '../layout-constants'
+import { PAGE_INSET_X, PAGE_MAX_W } from '../layout-constants'
 
 interface OverlaySplitLayoutProps {
   children: ReactNode
@@ -64,7 +64,8 @@ export function OverlayMain({ children, className }: OverlayMainProps) {
   return (
     <main
       className={cn(
-        'flex min-h-0 flex-1 flex-col overflow-hidden bg-transparent pb-3 pt-[calc(var(--titlebar-height)/2+1rem)]',
+        'mx-auto flex min-h-0 w-full flex-1 flex-col overflow-hidden bg-transparent pb-3 pt-[calc(var(--titlebar-height)/2+1rem)]',
+        PAGE_MAX_W,
         PAGE_INSET_X,
         className
       )}