diff --git a/.github/workflows/check.yml b/.github/workflows/check.yml
new file mode 100644
index 0000000..142d3d9
--- /dev/null
+++ b/.github/workflows/check.yml
@@ -0,0 +1,18 @@
+# https://docs.github.com/ja/pages/getting-started-with-github-pages/using-custom-workflows-with-github-pages
+name: Check
+
+on:
+  pull_request:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: "22"
+      - run: npm ci
+      - run: npm run build
diff --git a/src/style.css b/src/style.css
index caad04f..8e5e63f 100644
--- a/src/style.css
+++ b/src/style.css
@@ -28,7 +28,7 @@ canvas {
   left: 4px;
   width: 24px;
   height: 24px;
-  color: white;
+  color: #e5e7eb;
   cursor: pointer;
 }