Create GitHub Action to BuildCSS.yml

Github action automatically builds the CSS files in the `css/` directory from the `scss/` directory in merge and push requests using npm

.github/workflows/BuildCSS.yml

@@ -0,0 +1,41 @@
+name: Build CSS
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: write
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+
+    - name: Set up Node.js
+      uses: actions/setup-node@v2
+      with:
+        node-version: '20'
+
+    - name: Install dependencies
+      run: npm install
+
+    - name: Build CSS
+      run: npm run build
+
+    - name: Commit and push changes
+      run: |
+        git config --global user.name 'github-actions[bot]'
+        git config --global user.email 'github-actions[bot]@users.noreply.github.com'
+        git add .
+        git commit -m 'Build CSS'
+        git push
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}