diff --git a/packages/demo/.env.example b/packages/demo/.env.example
index 446732f6..95636f28 100644
--- a/packages/demo/.env.example
+++ b/packages/demo/.env.example
@@ -48,6 +48,12 @@ AUTH_ENDPOINT=https://auth.pds.example/oauth/authorize
 # light look, and client-metadata.json ships no branding CSS — the
 # auth-service then renders its default Certified styling. Available
 # presets: ocean, amber.
+#
+# Required (uncomment) to run the @client-branding e2e feature locally:
+# the suite asserts that auth-service inlines the demo's branding CSS,
+# which only happens when client-metadata.json advertises one. Without
+# it, every scenario in features/client-branding.feature fails with
+# "expect(html).toContain('body { background: #1a1208')" mismatches.
 # EPDS_CLIENT_THEME=amber
 
 # Session signing secret (generate with: openssl rand -base64 32)