fix CI

.gitlab-ci.yml

@@ -20,12 +20,11 @@ build and upload the contents:
     - chmod 700 /root/.ssh
     - ssh-keyscan tnw-tn1.tudelft.net >> /root/.ssh/known_hosts
     - chmod 644 /root/.ssh/known_hosts
-    - npm install gitbook-cli -g
+    - pip install -U mkdocs mkdocs-material python-markdown-math
 
   script:
     # Compile lectures
     - python code/band_structures.py
     - python code/bands_2d.py
-    - gitbook install
-    - gitbook build
-    - "rsync -rv _book/* solidstate@tnw-tn1.tudelft.net:"
+    - mkdocs build
+    - "rsync -rv site/* solidstate@tnw-tn1.tudelft.net:"