diff --git a/mkdocs.yml b/mkdocs.yml
index a55a33b005ebd1e595e10e7beed537bb06f66d39..f096745fb4389e280b67313c730cb729d3ef5be0 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -61,6 +61,7 @@ markdown_extensions:
   - toc:
       permalink: True
   - admonition
+  - attr_list
   - pymdownx.details
   - pymdownx.extra
   - abbr
diff --git a/src/5_atoms_and_lcao.md b/src/5_atoms_and_lcao.md
index d743c41d0c85a924a9303286e06f4658dfe783c7..75327e2d37d329023e5827c57b12c9338a2d06a9 100644
--- a/src/5_atoms_and_lcao.md
+++ b/src/5_atoms_and_lcao.md
@@ -96,7 +96,7 @@ Quantum numbers:
 
 Below is an illustration of several lowest energy orbitals in hydrogen:
 
-[![Hydrogen atomic orbitals](https://upload.wikimedia.org/wikipedia/commons/5/5c/Atomic_orbitals_n123_m-eigenstates.png)](https://commons.wikimedia.org/wiki/File:Atomic_orbitals_n123_m-eigenstates.png#/media/File:Atomic_orbitals_n123_m-eigenstates.png)
+[![Hydrogen atomic orbitals](https://upload.wikimedia.org/wikipedia/commons/5/5c/Atomic_orbitals_n123_m-eigenstates.png)](https://commons.wikimedia.org/wiki/File:Atomic_orbitals_n123_m-eigenstates.png#/media/File:Atomic_orbitals_n123_m-eigenstates.png){: style="width:50%"}
 
 (image source: Wikipedia © Geek3 CC-BY-SA)