diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 4dea3497..5eb6c989 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -53,9 +53,12 @@ jobs:
           mkdir -p _build/html/_notebooks
           cp -u _build/jupyter/*.ipynb _build/html/_notebooks
       # Build HTML (Website)
+      # BUG: rm .doctress to remove `sphinx` rendering issues for ipywidget mimetypes
+      # and clear the sphinx cache for building final HTML documents.
       - name: Build HTML
         shell: bash -l {0}
         run: |
+          rm -r _build/.doctrees
           jb build lectures --path-output ./
       - name: Save Build as Artifact
         uses: actions/upload-artifact@v1
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index 7ee7a4a6..adeaad72 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -63,9 +63,12 @@ jobs:
           mkdir -p _build/html/_notebooks
           cp -u _build/jupyter/*.ipynb _build/html/_notebooks
       # Build HTML (Website)
+      # BUG: rm .doctress to remove `sphinx` rendering issues for ipywidget mimetypes
+      # and clear the sphinx cache for building final HTML documents.
       - name: Build HTML
         shell: bash -l {0}
         run: |
+          rm -r _build/.doctrees
           jb build lectures --path-output ./
       - name: Deploy website to gh-pages
         uses: peaceiris/actions-gh-pages@v3