diff --git a/book/_config.yml b/book/_config.yml
index 3afcfa5..d16b980 100644
--- a/book/_config.yml
+++ b/book/_config.yml
@@ -19,6 +19,7 @@ sphinx:
   - download_link_replacer
   - jupyterbook_patches
   - teachbooks_sphinx_grasple
+  - sphinx_image_inverter
   config:
     html_js_files:
     - https://cdnjs.cloudflare.com/ajax/libs/require.js/2.3.4/require.min.js
diff --git a/book/examples/theory_questions.md b/book/examples/theory_questions.md
index 05f9417..a30cf2c 100644
--- a/book/examples/theory_questions.md
+++ b/book/examples/theory_questions.md
@@ -12,11 +12,13 @@ Truss structures are structures assembled of straight elements connected in node
 Examples of these structures are commonly found in rail bridges like the one below:
 
 ```{figure} theory_questions_images/pic0.jpg
+:class: dark-light
 :width: 400
 ```
 Furthermore, these structures are commonly found in building as well, both invisible and visible:
 
 ```{figure} theory_questions_images/pic1.jpg
+:class: dark-light
 :width: 400
 ```
 
diff --git a/requirements.txt b/requirements.txt
index 7251625..0a63bae 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,6 +5,7 @@ jupyterlite-sphinx
 jupyterbook_patches
 download_link_replacer
 teachbooks-sphinx-grasple
+sphinx-image-inverter
 
 
 --extra-index-url https://gitlab.tudelft.nl/api/v4/projects/11239/packages/pypi/simple