diff --git a/CHANGELOG.md b/CHANGELOG.md
index d5fb01a..90c7aec 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,13 @@ All notable changes to `pdf-tools` are documented here.
 
 The project follows a pragmatic versioning scheme while the app is still below `1.0.0`: minor versions mark coherent user-facing milestones; patch versions mark fixes and small improvements.
 
+## 0.4.3 — Aligned Toolbox content width
+
+### Changed
+
+- Expanded the PDF workspace's maximum content width from `900px` to `90rem` so it aligns with the shared Toolbox shell bar and central catalogue.
+- Bumped the app/package version to `0.4.3`.
+
 ## 0.4.2 — Corrected Toolbox header orientation
 
 ### Changed
diff --git a/README.md b/README.md
index cd02cc5..e19b8ba 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@
 
 Current hosted version: <https://pdftools.add-ideas.de>
 
-Current development release: **v0.4.2 — corrected Toolbox header orientation**. See [`CHANGELOG.md`](CHANGELOG.md) for milestone history.
+Current development release: **v0.4.3 — aligned Toolbox content width**. See [`CHANGELOG.md`](CHANGELOG.md) for milestone history.
 
 Active work is tracked in Gitea issues. Durable project context is mirrored into the Gitea wiki from repository docs, including [`ROADMAP.md`](ROADMAP.md).
 
@@ -257,10 +257,10 @@ The application version shown in the header is defined in `src/version.ts`. The
 The current development baseline is:
 
 ```text
-v0.4.2 — corrected Toolbox header orientation and light/dark/system themes
+v0.4.3 — aligned Toolbox content width and light/dark/system themes
 ```
 
-This branch preserves the browser-only workspace baseline and PDF.js compatibility setup while moving the app to Toolbox SDK `0.2.2`. The displayed app/package version is `0.4.2`; the shared header keeps the Toolbox icon and `add·ideas Toolbox` label in a fixed far-left block, the app title and one tagline centered, and Help, the PDF source link, Apps, and Personalize in a fixed far-right cluster. Workspace state, thumbnail handling, generated download URLs, page-grid components, tests, type-checking, linting, and formatting remain separated enough to support additional feature work without turning `App.tsx` back into a monolith.
+This branch preserves the browser-only workspace baseline and PDF.js compatibility setup while using Toolbox SDK `0.2.2`. The displayed app/package version is `0.4.3`; the shared header keeps the Toolbox icon and `add·ideas Toolbox` label in a fixed far-left block, the app title and one tagline centered, and Help, the PDF source link, Apps, and Personalize in a fixed far-right cluster. The PDF workspace now shares the shell bar's `90rem` maximum width. Workspace state, thumbnail handling, generated download URLs, page-grid components, tests, type-checking, linting, and formatting remain separated enough to support additional feature work without turning `App.tsx` back into a monolith.
 
 ## Project structure
 
diff --git a/package-lock.json b/package-lock.json
index cc20845..6a86624 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "pdf-tools",
-  "version": "0.4.2",
+  "version": "0.4.3",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "pdf-tools",
-      "version": "0.4.2",
+      "version": "0.4.3",
       "license": "AGPL-3.0-only",
       "dependencies": {
         "@add-ideas/toolbox-contract": "^0.2.2",
diff --git a/package.json b/package.json
index 681e89a..fbfd738 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "pdf-tools",
-  "version": "0.4.2",
+  "version": "0.4.3",
   "private": true,
   "license": "AGPL-3.0-only",
   "type": "module",
diff --git a/public/toolbox-app.json b/public/toolbox-app.json
index faba993..485a836 100644
--- a/public/toolbox-app.json
+++ b/public/toolbox-app.json
@@ -28,5 +28,5 @@
     "repository": "https://git.add-ideas.de/zemion/pdf-tools",
     "license": "AGPL-3.0-only"
   },
-  "version": "0.4.2"
+  "version": "0.4.3"
 }
diff --git a/src/styles.css b/src/styles.css
index 4716fa3..0ca97a8 100644
--- a/src/styles.css
+++ b/src/styles.css
@@ -168,7 +168,7 @@ body {
 
 .pdf-toolbox-shell .toolbox-shell__main {
   padding: 0.75rem;
-  max-width: 900px;
+  max-width: 90rem;
   display: flex;
   flex-direction: column;
   gap: 0.75rem;
diff --git a/src/version.ts b/src/version.ts
index 77df246..66935b6 100644
--- a/src/version.ts
+++ b/src/version.ts
@@ -1 +1 @@
-export const APP_VERSION = '0.4.2';
+export const APP_VERSION = '0.4.3';
diff --git a/tests/layoutStyles.test.ts b/tests/layoutStyles.test.ts
new file mode 100644
index 0000000..e1daac9
--- /dev/null
+++ b/tests/layoutStyles.test.ts
@@ -0,0 +1,13 @@
+import { readFile } from 'node:fs/promises';
+import { describe, expect, it } from 'vitest';
+
+describe('Toolbox layout styles', () => {
+  it('keeps the PDF workspace aligned to the 90rem shell width', async () => {
+    const stylesheet = await readFile('src/styles.css', 'utf8');
+    const mainRule = stylesheet.match(
+      /\.pdf-toolbox-shell \.toolbox-shell__main\s*\{(?<body>[^}]*)\}/u
+    );
+
+    expect(mainRule?.groups?.body).toMatch(/\bmax-width:\s*90rem\s*;/u);
+  });
+});