diff --git a/backend/e2e/v8-coverage-shutdown.cjs b/backend/e2e/v8-coverage-shutdown.cjs
index 22cad4b..eb8c704 100644
--- a/backend/e2e/v8-coverage-shutdown.cjs
+++ b/backend/e2e/v8-coverage-shutdown.cjs
@@ -1,11 +1,13 @@
+/* eslint-disable no-console */
 const v8 = require('node:v8');
 const http = require('node:http');
 
 const oauthMockPort = Number(process.env.E2E_OAUTH_MOCK_PORT ?? 0);
 if (oauthMockPort > 0) {
   const issuer = `http://localhost:${oauthMockPort}`;
-  http.createServer(async (request, response) => {
+  const server = http.createServer(async (request, response) => {
     response.setHeader('content-type', 'application/json');
+    response.setHeader('x-content-type-options', 'nosniff');
 
     if (request.url === '/.well-known/oauth-authorization-server') {
       response.end(JSON.stringify({
@@ -39,7 +41,13 @@ if (oauthMockPort > 0) {
 
     response.statusCode = 404;
     response.end(JSON.stringify({ error: 'not found' }));
-  }).listen(oauthMockPort, '127.0.0.1', () => {
+  });
+
+  server.on('error', (err) => {
+    console.error('Mock OAuth server error:', err);
+  });
+
+  server.listen(oauthMockPort, '127.0.0.1', () => {
     console.log(JSON.stringify({ event: 'mock-oauth-pds-listening', oauthMockPort }));
   });
 }
@@ -48,3 +56,4 @@ process.once('SIGTERM', () => {
   v8.takeCoverage();
   process.exit(0);
 });
+
diff --git a/frontend/pnpm-lock.yaml b/frontend/pnpm-lock.yaml
index ebfd6d7..0737aa7 100644
--- a/frontend/pnpm-lock.yaml
+++ b/frontend/pnpm-lock.yaml
@@ -5,10 +5,10 @@ settings:
   excludeLinksFromLockfile: false
 
 overrides:
-  postcss: '>=8.5.10'
+  postcss: ^8.5.26
   lodash: '>=4.17.24'
   find-my-way: '>=9.6.1'
-  sharp: '>=0.35.0'
+  sharp: ^0.35.3
   valibot: '>=1.4.2'
   hono: '>=4.12.21'
   '@hono/node-server': '>=1.19.10'
@@ -3931,24 +3931,24 @@ packages:
     resolution: {integrity: sha512-oIAOTqgIo7q2EOwbhb8UalYePMvYoIeRY2YKntdpFQXNosSu3vLrniGgmH9OKs/qAkfoj5oB3le/7mINW1LCfw==}
     engines: {node: ^12 || ^14 || >= 16}
     peerDependencies:
-      postcss: '>=8.5.10'
+      postcss: ^8.5.26
 
   postcss-mixins@12.1.2:
     resolution: {integrity: sha512-90pSxmZVfbX9e5xCv7tI5RV1mnjdf16y89CJKbf/hD7GyOz1FCxcYMl8ZYA8Hc56dbApTKKmU9HfvgfWdCxlwg==}
     engines: {node: ^20.0 || ^22.0 || >=24.0}
     peerDependencies:
-      postcss: '>=8.5.10'
+      postcss: ^8.5.26
 
   postcss-nested@7.0.2:
     resolution: {integrity: sha512-5osppouFc0VR9/VYzYxO03VaDa3e8F23Kfd6/9qcZTUI8P58GIYlArOET2Wq0ywSl2o2PjELhYOFI4W7l5QHKw==}
     engines: {node: '>=18.0'}
     peerDependencies:
-      postcss: '>=8.5.10'
+      postcss: ^8.5.26
 
   postcss-preset-mantine@1.18.0:
     resolution: {integrity: sha512-sP6/s1oC7cOtBdl4mw/IRKmKvYTuzpRrH/vT6v9enMU/EQEQ31eQnHcWtFghOXLH87AAthjL/Q75rLmin1oZoA==}
     peerDependencies:
-      postcss: '>=8.5.10'
+      postcss: ^8.5.26
 
   postcss-selector-parser@7.1.5:
     resolution: {integrity: sha512-KvvtD7SrlBP7dlgkBghEE3r84CABm5SmV2aNcG4oCA+qDnJ/tvKonFVvwWAyyWUEwxuNawdfEAZKP9zM3oZ2Uw==}
@@ -3958,7 +3958,7 @@ packages:
     resolution: {integrity: sha512-5GLLXaS8qmzHMOjVxqkk1TZPf1jMqesiI7qLhnlyERalG0sMbHIbJqrcnrpmZdKCLglHnRHoEBB61RtGTsj++A==}
     engines: {node: '>=14.0'}
     peerDependencies:
-      postcss: '>=8.5.10'
+      postcss: ^8.5.26
 
   postcss@8.5.26:
     resolution: {integrity: sha512-u82N74LFzG8ca+dD8puPnplTXoGH4fTPpVGuIbt36G3qvNlkvfD0lEAZSxaly3KX8TS/L1A1gsCEmvKmBcVbkQ==}
@@ -4350,7 +4350,7 @@ packages:
     resolution: {integrity: sha512-ctS5RYCBVvPoZAnzIaX5QSShK8ZiZxD5HUqSxlusvEMC+QZQIPCPOIJg6aceFX+K2rf4+SH89eu++h1Zmsr2nw==}
     engines: {node: '>=18.0'}
     peerDependencies:
-      postcss: '>=8.5.10'
+      postcss: ^8.5.26
 
   supports-color@7.2.0:
     resolution: {integrity: sha512-qpCAvRl9stuOHveKsn7HncJRvv501qIacKzQlO/+Lwxc9+0q2wLyv4Dfvt80/DPn2pqOBsJdDiogXGR9+OvwRw==}
diff --git a/frontend/pnpm-workspace.yaml b/frontend/pnpm-workspace.yaml
index 51b7ad0..2da8df1 100644
--- a/frontend/pnpm-workspace.yaml
+++ b/frontend/pnpm-workspace.yaml
@@ -17,10 +17,10 @@ minimumReleaseAgeExclude:
   - '@atcute/bluesky@4.0.6'
 
 overrides:
-  postcss: ">=8.5.10"
+  postcss: "^8.5.26"
   lodash: ">=4.17.24"
   find-my-way: ">=9.6.1"
-  sharp: ">=0.35.0"
+  sharp: "^0.35.3"
   valibot: ">=1.4.2"
   hono: ">=4.12.21"
   "@hono/node-server": ">=1.19.10"