diff --git a/.github/workflows/cache.yml b/.github/workflows/cache.yml
index f968aa655..a9a19165b 100644
--- a/.github/workflows/cache.yml
+++ b/.github/workflows/cache.yml
@@ -2,7 +2,9 @@ name: Build Cache [using jupyter-book]
 on:
   push:
     branches:
+      - cache_test_3
       - main
+
 jobs:
   tests:
     runs-on: ubuntu-latest
@@ -21,6 +23,9 @@ jobs:
       - name: graphviz Support # TODO: required?
         run: |
           sudo apt-get -qq update && sudo apt-get install -y graphviz
+      - name: Install sphinx from branch
+        run: |
+          pip install git+https://github.com/kp992/sphinx.git@testcache
       - name: Install latex dependencies
         run: |
           sudo apt-get -qq update
diff --git a/environment.yml b/environment.yml
index f60099b5e..bb177cba8 100644
--- a/environment.yml
+++ b/environment.yml
@@ -13,11 +13,12 @@ dependencies:
     - sphinx-tojupyter==0.3.0
     - sphinxext-rediraffe==0.2.7
     - sphinx-exercise==0.4.1
-    - sphinx-proof==0.2.0
+    - sphinx-proof==0.1.3
     - ghp-import==1.1.0
     - sphinxcontrib-youtube==1.1.0
     - sphinx-togglebutton==0.3.1
     - sphinx_reredirects==0.1.3
+    - nbdime==4.0.1
     # Sandpit Requirements
     # - PuLP
     # - cvxpy
diff --git a/lectures/_config.yml b/lectures/_config.yml
index ecd808f0f..84d407d7e 100644
--- a/lectures/_config.yml
+++ b/lectures/_config.yml
@@ -45,7 +45,6 @@ sphinx:
       width: 80%
     nb_code_prompt_show: "Show {type}"
     suppress_warnings: [mystnb.unknown_mime_type, myst.domains]
-    proof_minimal_theme: true
     # -------------
     html_js_files:
       - https://cdnjs.cloudflare.com/ajax/libs/require.js/2.3.4/require.min.js