diff --git a/client/src/pages/SharedTripPage.test.tsx b/client/src/pages/SharedTripPage.test.tsx
index 40c3f770a..2ecfe7d83 100644
--- a/client/src/pages/SharedTripPage.test.tsx
+++ b/client/src/pages/SharedTripPage.test.tsx
@@ -1483,4 +1483,19 @@ describe('SharedTripPage', () => {
       expect(document.querySelector('a[href^="javascript:"]')).toBeNull();
     });
   });
+
+  // ── #2345: the header has to clip the decoration it bleeds ──────────────
+
+  describe('FE-PAGE-SHARED-042: the header clips the circles it bleeds (#2345)', () => {
+    it('does not let them widen the page', async () => {
+      await open('overflow-token', payload({}));
+
+      // Both circles sit outside the header on purpose, so the page only stays
+      // as wide as the viewport if the header itself is the clip. The header is
+      // the first gradient panel on the page and carries the trip title.
+      const header = document.querySelector<HTMLElement>('div[style*="linear-gradient(135deg"]');
+      expect(header?.textContent).toContain('Shared Paris Trip');
+      expect(header?.style.overflow).toBe('hidden');
+    });
+  });
 });
diff --git a/client/src/pages/SharedTripPage.tsx b/client/src/pages/SharedTripPage.tsx
index 9e04a494f..f0e0d384b 100644
--- a/client/src/pages/SharedTripPage.tsx
+++ b/client/src/pages/SharedTripPage.tsx
@@ -205,6 +205,9 @@ export default function SharedTripPage() {
           padding: '32px 20px 28px',
           textAlign: 'center',
           position: 'relative',
+          // The decoration circles bleed past this box on purpose; without the clip
+          // they widened the page by 60px on a phone (#2345).
+          overflow: 'hidden',
         }}
       >
         {/* Cover image background */}