diff --git a/assets/sass/layout.scss b/assets/sass/layout.scss
index 1b1d38e279..27c524b055 100644
--- a/assets/sass/layout.scss
+++ b/assets/sass/layout.scss
@@ -471,6 +471,7 @@ table.benchmarks {
 
 #content-wrapper {
   display: flex;
+  justify-content: space-between;
 }
 
 // Breakpoint ----------------
diff --git a/tests/git-scm.spec.js b/tests/git-scm.spec.js
index 663fb83c6d..5423d8b2b6 100644
--- a/tests/git-scm.spec.js
+++ b/tests/git-scm.spec.js
@@ -349,3 +349,20 @@ test('dark mode', async({ page }) => {
   const autoLightBrightness = await getPageBrightness();
   expect(autoLightBrightness).toBeCloseTo(0.85, 0.1);
 });
+
+test('right-side alignment of header and content areas', async ({ page }) => {
+  await page.goto(`${url}about`)
+
+  // The sidebar (aside) and #content sit inside #content-wrapper (display: flex).
+  // Their combined widths must fill the container so the right edges align.
+  const containerBox = await page.locator('#content-wrapper').boundingBox()
+  const contentBox = await page.locator('#content').boundingBox()
+
+  expect(containerBox).not.toBeNull()
+  expect(contentBox).not.toBeNull()
+
+  const containerRight = containerBox.x + containerBox.width
+  const contentRight = contentBox.x + contentBox.width
+
+  expect(Math.abs(containerRight - contentRight)).toBeLessThanOrEqual(1)
+})