implement new highlight for self-check questions

docs/lecture_7.md

@@ -95,7 +95,8 @@ Here $E_G$ is the band gap, and the top of the valence band is at $E=0$.
 
 Observe that because we are describing particles in the valence band as holes, $m_h > 0$ and $E_h > 0$.
 
-**Question:** a photon gives a single electron enough energy to move from the valence band to the conduction band. How many particles does this process create?
+??? question "a photon gives a single electron enough energy to move from the valence band to the conduction band. How many particles does this process create?"
+    Two: one electron and one hole.
 
 ## Semiconductor density of states and Fermi level
 
@@ -350,4 +351,4 @@ Conductance combines the contributions of electrons and holes, and allows to det
 
 A $pn$-junction has a **depletion layer** in its middle with the potential in a $pn$-junction having the following shape (where the transition region is made out of two parabolas):
 
-![](figures/band_diagram_solution.svg)
\ No newline at end of file
+![](figures/band_diagram_solution.svg)

mkdocs.yml

@@ -23,6 +23,8 @@ markdown_extensions:
       enable_dollar_delimiter: True
   - toc:
       permalink: True
+  - admonition
+  - pymdownx.details
 
 extra_javascript:
   - 'https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.3/MathJax.js?config=TeX-AMS_HTML'