diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 5790367..d24c14b 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -9,10 +9,12 @@ jobs:
     timeout-minutes: 60
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
+      - uses: actions/checkout@v5
+      - uses: actions/setup-node@v5
         with:
-          node-version: 20
+          node-version: 24
       - run: yarn install --frozen-lockfile
+      - run: yarn tsc
+      - run: yarn format-check
       - run: yarn playwright install --with-deps
       - run: yarn playwright test
diff --git a/.gitignore b/.gitignore
index 0d6c6e2..7f16beb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,6 +2,7 @@
 *.log*
 node_modules/
 
+/src/manifest.json
 /tmp/
 /dist/
 
diff --git a/jsconfig.json b/jsconfig.json
deleted file mode 100644
index 7cb5f45..0000000
--- a/jsconfig.json
+++ /dev/null
@@ -1,13 +0,0 @@
-{
-  "compilerOptions": {
-    "target": "esnext",
-    "module": "esnext",
-    "strict": true,
-    "checkJs": true
-  },
-  "typeAcquisition": {
-    "include": ["chrome"]
-  },
-  "include": ["src/**/*.js", "tests/**/*.js"],
-  "exclude": ["node_modules"]
-}
diff --git a/mise.toml b/mise.toml
new file mode 100644
index 0000000..6ea5a7e
--- /dev/null
+++ b/mise.toml
@@ -0,0 +1,2 @@
+[tools]
+node = "24"
diff --git a/package.json b/package.json
index 2c02678..f78e3d2 100644
--- a/package.json
+++ b/package.json
@@ -13,10 +13,10 @@
     "format-check": "prettier --check ."
   },
   "devDependencies": {
-    "@playwright/test": "^1.45.1",
-    "@types/chrome": "^0.0.268",
-    "@types/node": "^20.14.9",
-    "prettier": "^3.3.2",
-    "typescript": "^5.5.3"
+    "@playwright/test": "^1.56.0",
+    "@types/chrome": "^0.1.24",
+    "@types/node": "^24.7.2",
+    "prettier": "^3.6.2",
+    "typescript": "^5.9.3"
   }
 }
diff --git a/src/background.js b/src/background.js
index 5d407bc..b9415c8 100644
--- a/src/background.js
+++ b/src/background.js
@@ -13,7 +13,7 @@ chrome.runtime.onInstalled.addListener(() => {
 
 const cache = new Map();
 
-chrome.runtime.onMessage.addListener((message, sender, sendResponse) => {
+chrome.runtime.onMessage.addListener((message, _sender, sendResponse) => {
   sendResponse(cache.get(message));
 });
 
diff --git a/src/content.js b/src/content.js
index 0ad805b..7e68349 100644
--- a/src/content.js
+++ b/src/content.js
@@ -60,10 +60,13 @@ function getComputedBackgroundImages(element, pseudo) {
     style.getPropertyValue('background-image'),
     style.getPropertyValue('content'),
   ];
+  /** @type {Set<string>} */
   const images = new Set();
   for (const value of values) {
     for (const [, url] of value.matchAll(/url\("(.+?)"\)/g)) {
-      images.add(url.replaceAll('\\"', '"'));
+      if (url) {
+        images.add(url.replaceAll('\\"', '"'));
+      }
     }
   }
   return images;
@@ -85,15 +88,22 @@ if (chrome.runtime) {
   let x = 0;
   let y = 0;
 
-  document.addEventListener('contextmenu', (event) => {
-    if (event.target instanceof Element) {
-      root = event.target.ownerDocument;
-    }
-    x = event.clientX;
-    y = event.clientY;
-  });
+  window.addEventListener(
+    'contextmenu',
+    (event) => {
+      if (event.shiftKey) {
+        event.stopPropagation();
+      }
+      if (event.target instanceof Element) {
+        root = event.target.ownerDocument;
+      }
+      x = event.clientX;
+      y = event.clientY;
+    },
+    { capture: true },
+  );
 
-  chrome.runtime.onMessage.addListener((message, sender, sendResponse) => {
+  chrome.runtime.onMessage.addListener((_message, _sender, sendResponse) => {
     sendResponse([...getBackgroundImages(root, x, y)]);
   });
 }
diff --git a/src/manifest.chrome.json b/src/manifest.chrome.json
index feb631d..b26f9f8 100644
--- a/src/manifest.chrome.json
+++ b/src/manifest.chrome.json
@@ -1,7 +1,7 @@
 {
   "manifest_version": 3,
   "name": "__MSG_extName__",
-  "version": "3.0.4",
+  "version": "3.1.0",
   "description": "__MSG_extDescription__",
   "default_locale": "en",
   "permissions": ["contextMenus"],
diff --git a/src/manifest.firefox.json b/src/manifest.firefox.json
index d0e92a2..f12aab7 100644
--- a/src/manifest.firefox.json
+++ b/src/manifest.firefox.json
@@ -1,7 +1,7 @@
 {
   "manifest_version": 3,
   "name": "__MSG_extName__",
-  "version": "3.0.4",
+  "version": "3.1.0",
   "description": "__MSG_extDescription__",
   "default_locale": "en",
   "permissions": ["contextMenus"],
diff --git a/src/manifest.json b/src/manifest.json
deleted file mode 100644
index feb631d..0000000
--- a/src/manifest.json
+++ /dev/null
@@ -1,26 +0,0 @@
-{
-  "manifest_version": 3,
-  "name": "__MSG_extName__",
-  "version": "3.0.4",
-  "description": "__MSG_extDescription__",
-  "default_locale": "en",
-  "permissions": ["contextMenus"],
-  "background": {
-    "service_worker": "background.js"
-  },
-  "content_scripts": [
-    {
-      "matches": ["http://*/*", "https://*/*", "file:///*/*"],
-      "js": ["content.js"],
-      "run_at": "document_start",
-      "all_frames": true
-    }
-  ],
-  "icons": {
-    "16": "icons/icon16.png",
-    "32": "icons/icon32.png",
-    "48": "icons/icon48.png",
-    "128": "icons/icon128.png"
-  },
-  "incognito": "split"
-}
diff --git a/src/viewer/error.js b/src/viewer/error.js
index f0f9266..dea8474 100644
--- a/src/viewer/error.js
+++ b/src/viewer/error.js
@@ -8,7 +8,7 @@ export function showError(error) {
   $('error').classList.remove('hidden');
   $('nav').classList.add('hidden');
 
-  if (navigator.userAgent.includes('Gecko')) {
+  if (navigator.userAgent.includes('Firefox')) {
     $('error-firefox').classList.remove('hidden');
   }
 }
diff --git a/tests/getBackgroundImages.spec.ts b/tests/getBackgroundImages.spec.ts
index 4ae80e8..b57aeb8 100644
--- a/tests/getBackgroundImages.spec.ts
+++ b/tests/getBackgroundImages.spec.ts
@@ -1,6 +1,12 @@
 import { test, expect } from '@playwright/test';
 import { basename } from 'node:path';
 
+declare function getBackgroundImages(
+  root: Document | ShadowRoot,
+  x: number,
+  y: number,
+): Set<string>;
+
 interface TestCase {
   title: string;
   point: [x: number, y: number];
@@ -62,7 +68,6 @@ for (const { title, point, expected, skip } of testCases) {
     });
 
     const actual = await page.evaluate(
-      // @ts-ignore
       ([x, y]) => [...getBackgroundImages(document, x, y)],
       point,
     );
diff --git a/tests/locales.test.js b/tests/locales.test.ts
similarity index 95%
rename from tests/locales.test.js
rename to tests/locales.test.ts
index 3fceb4d..02f7810 100644
--- a/tests/locales.test.js
+++ b/tests/locales.test.ts
@@ -20,7 +20,7 @@ test('locales', async (t) => {
     await t.test(locale, async (t) => {
       const { default: messages } = await import(
         import.meta.resolve(`../src/_locales/${locale}/messages.json`),
-        { assert: { type: 'json' } }
+        { with: { type: 'json' } }
       );
 
       for (const key of keys) {
diff --git a/tests/tsconfig.json b/tests/tsconfig.json
new file mode 100644
index 0000000..c00178d
--- /dev/null
+++ b/tests/tsconfig.json
@@ -0,0 +1,8 @@
+{
+  "extends": "../tsconfig.json",
+  "compilerOptions": {
+    "module": "nodenext",
+    "types": ["node"]
+  },
+  "include": ["**/*.ts"]
+}
diff --git a/tsconfig.json b/tsconfig.json
new file mode 100644
index 0000000..e7114c4
--- /dev/null
+++ b/tsconfig.json
@@ -0,0 +1,32 @@
+{
+  "compilerOptions": {
+    // Environment Settings
+    "module": "esnext",
+    "target": "esnext",
+    "types": ["chrome"],
+
+    // Stricter Typechecking Options
+    "noUncheckedIndexedAccess": true,
+    "exactOptionalPropertyTypes": true,
+
+    // Style Options
+    "noImplicitReturns": true,
+    "noImplicitOverride": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "noFallthroughCasesInSwitch": true,
+    "noPropertyAccessFromIndexSignature": true,
+
+    // Recommended Options
+    "strict": true,
+    "noUncheckedSideEffectImports": true,
+    "moduleDetection": "force",
+    "skipLibCheck": true,
+
+    // Other Options
+    "allowJs": true,
+    "checkJs": true,
+    "noEmit": true
+  },
+  "include": ["src/**/*.js"]
+}
diff --git a/yarn.lock b/yarn.lock
index fcefb93..cc359b3 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2,17 +2,17 @@
 # yarn lockfile v1
 
 
-"@playwright/test@^1.45.1":
-  version "1.45.1"
-  resolved "https://registry.yarnpkg.com/@playwright/test/-/test-1.45.1.tgz#819b90fa43d17000fce5ebd127043fd661938b7a"
-  integrity sha512-Wo1bWTzQvGA7LyKGIZc8nFSTFf2TkthGIFBR+QVNilvwouGzFd4PYukZe3rvf5PSqjHi1+1NyKSDZKcQWETzaA==
+"@playwright/test@^1.56.0":
+  version "1.56.0"
+  resolved "https://registry.yarnpkg.com/@playwright/test/-/test-1.56.0.tgz#891fe101bddf3eee3dd609e7a145f705dc0f3054"
+  integrity sha512-Tzh95Twig7hUwwNe381/K3PggZBZblKUe2wv25oIpzWLr6Z0m4KgV1ZVIjnR6GM9ANEqjZD7XsZEa6JL/7YEgg==
   dependencies:
-    playwright "1.45.1"
+    playwright "1.56.0"
 
-"@types/chrome@^0.0.268":
-  version "0.0.268"
-  resolved "https://registry.yarnpkg.com/@types/chrome/-/chrome-0.0.268.tgz#d5855546f30c83e181cadd77127a162c25b480d2"
-  integrity sha512-7N1QH9buudSJ7sI8Pe4mBHJr5oZ48s0hcanI9w3wgijAlv1OZNUZve9JR4x42dn5lJ5Sm87V1JNfnoh10EnQlA==
+"@types/chrome@^0.1.24":
+  version "0.1.24"
+  resolved "https://registry.yarnpkg.com/@types/chrome/-/chrome-0.1.24.tgz#71c93111c40a057a8a45c4ab74eb7fe0aaf0048a"
+  integrity sha512-9iO9HL2bMeGS4C8m6gNFWUyuPE5HEUFk+rGh+7oriUjg+ata4Fc9PoVlu8xvGm7yoo3AmS3J6fAjoFj61NL2rw==
   dependencies:
     "@types/filesystem" "*"
     "@types/har-format" "*"
@@ -30,47 +30,47 @@
   integrity sha512-xFU8ZXTw4gd358lb2jw25nxY9QAgqn2+bKKjKOYfNCzN4DKCFetK7sPtrlpg66Ywe3vWY9FNxprZawAh9wfJ3g==
 
 "@types/har-format@*":
-  version "1.2.15"
-  resolved "https://registry.yarnpkg.com/@types/har-format/-/har-format-1.2.15.tgz#f352493638c2f89d706438a19a9eb300b493b506"
-  integrity sha512-RpQH4rXLuvTXKR0zqHq3go0RVXYv/YVqv4TnPH95VbwUxZdQlK1EtcMvQvMpDngHbt13Csh9Z4qT9AbkiQH5BA==
+  version "1.2.16"
+  resolved "https://registry.yarnpkg.com/@types/har-format/-/har-format-1.2.16.tgz#b71ede8681400cc08b3685f061c31e416cf94944"
+  integrity sha512-fluxdy7ryD3MV6h8pTfTYpy/xQzCFC7m89nOH9y94cNqJ1mDIDPut7MnRHI3F6qRmh/cT2fUjG1MLdCNb4hE9A==
 
-"@types/node@^20.14.9":
-  version "20.14.9"
-  resolved "https://registry.yarnpkg.com/@types/node/-/node-20.14.9.tgz#12e8e765ab27f8c421a1820c99f5f313a933b420"
-  integrity sha512-06OCtnTXtWOZBJlRApleWndH4JsRVs1pDCc8dLSQp+7PpUpX3ePdHyeNSFTeSe7FtKyQkrlPvHwJOW3SLd8Oyg==
+"@types/node@^24.7.2":
+  version "24.7.2"
+  resolved "https://registry.yarnpkg.com/@types/node/-/node-24.7.2.tgz#5adf66b6e2ac5cab1d10a2ad3682e359cb652f4a"
+  integrity sha512-/NbVmcGTP+lj5oa4yiYxxeBjRivKQ5Ns1eSZeB99ExsEQ6rX5XYU1Zy/gGxY/ilqtD4Etx9mKyrPxZRetiahhA==
   dependencies:
-    undici-types "~5.26.4"
+    undici-types "~7.14.0"
 
 fsevents@2.3.2:
   version "2.3.2"
   resolved "https://registry.yarnpkg.com/fsevents/-/fsevents-2.3.2.tgz#8a526f78b8fdf4623b709e0b975c52c24c02fd1a"
   integrity sha512-xiqMQR4xAeHTuB9uWm+fFRcIOgKBMiOBP+eXiyT7jsgVCq1bkVygt00oASowB7EdtpOHaaPgKt812P9ab+DDKA==
 
-playwright-core@1.45.1:
-  version "1.45.1"
-  resolved "https://registry.yarnpkg.com/playwright-core/-/playwright-core-1.45.1.tgz#549a2701556b58245cc75263f9fc2795c1158dc1"
-  integrity sha512-LF4CUUtrUu2TCpDw4mcrAIuYrEjVDfT1cHbJMfwnE2+1b8PZcFzPNgvZCvq2JfQ4aTjRCCHw5EJ2tmr2NSzdPg==
+playwright-core@1.56.0:
+  version "1.56.0"
+  resolved "https://registry.yarnpkg.com/playwright-core/-/playwright-core-1.56.0.tgz#14b40ea436551b0bcefe19c5bfb8d1804c83739c"
+  integrity sha512-1SXl7pMfemAMSDn5rkPeZljxOCYAmQnYLBTExuh6E8USHXGSX3dx6lYZN/xPpTz1vimXmPA9CDnILvmJaB8aSQ==
 
-playwright@1.45.1:
-  version "1.45.1"
-  resolved "https://registry.yarnpkg.com/playwright/-/playwright-1.45.1.tgz#aaa6b0d6db14796b599d80c6679e63444e942534"
-  integrity sha512-Hjrgae4kpSQBr98nhCj3IScxVeVUixqj+5oyif8TdIn2opTCPEzqAqNMeK42i3cWDCVu9MI+ZsGWw+gVR4ISBg==
+playwright@1.56.0:
+  version "1.56.0"
+  resolved "https://registry.yarnpkg.com/playwright/-/playwright-1.56.0.tgz#71c533c61da33e95812f8c6fa53960e073548d9a"
+  integrity sha512-X5Q1b8lOdWIE4KAoHpW3SE8HvUB+ZZsUoN64ZhjnN8dOb1UpujxBtENGiZFE+9F/yhzJwYa+ca3u43FeLbboHA==
   dependencies:
-    playwright-core "1.45.1"
+    playwright-core "1.56.0"
   optionalDependencies:
     fsevents "2.3.2"
 
-prettier@^3.3.2:
-  version "3.3.2"
-  resolved "https://registry.yarnpkg.com/prettier/-/prettier-3.3.2.tgz#03ff86dc7c835f2d2559ee76876a3914cec4a90a"
-  integrity sha512-rAVeHYMcv8ATV5d508CFdn+8/pHPpXeIid1DdrPwXnaAdH7cqjVbpJaT5eq4yRAFU/lsbwYwSF/n5iNrdJHPQA==
+prettier@^3.6.2:
+  version "3.6.2"
+  resolved "https://registry.yarnpkg.com/prettier/-/prettier-3.6.2.tgz#ccda02a1003ebbb2bfda6f83a074978f608b9393"
+  integrity sha512-I7AIg5boAr5R0FFtJ6rCfD+LFsWHp81dolrFD8S79U9tb8Az2nGrJncnMSnys+bpQJfRUzqs9hnA81OAA3hCuQ==
 
-typescript@^5.5.3:
-  version "5.5.3"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-5.5.3.tgz#e1b0a3c394190838a0b168e771b0ad56a0af0faa"
-  integrity sha512-/hreyEujaB0w76zKo6717l3L0o/qEUtRgdvUBvlkhoWeOVMjMuHNHk0BRBzikzuGDqNmPQbg5ifMEqsHLiIUcQ==
+typescript@^5.9.3:
+  version "5.9.3"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-5.9.3.tgz#5b4f59e15310ab17a216f5d6cf53ee476ede670f"
+  integrity sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw==
 
-undici-types@~5.26.4:
-  version "5.26.5"
-  resolved "https://registry.yarnpkg.com/undici-types/-/undici-types-5.26.5.tgz#bcd539893d00b56e964fd2657a4866b221a65617"
-  integrity sha512-JlCMO+ehdEIKqlFxk6IfVoAUVmgz7cU7zD/h9XZ0qzeosSHmUJVOzSQvvYSYWXkFXC+IfLKSIffhv0sVZup6pA==
+undici-types@~7.14.0:
+  version "7.14.0"
+  resolved "https://registry.yarnpkg.com/undici-types/-/undici-types-7.14.0.tgz#4c037b32ca4d7d62fae042174604341588bc0840"
+  integrity sha512-QQiYxHuyZ9gQUIrmPo3IA+hUl4KYk8uSA7cHrcKd/l3p1OTpZcM0Tbp9x7FAtXdAYhlasd60ncPpgu6ihG6TOA==