Updated blockquotes.

config/en/mkdocs.yaml

@@ -41,6 +41,8 @@ markdown_extensions:
   - pymdownx.details
   - pymdownx.superfences
 
+extra_css:
+  - stylesheets/extra.css
 
 extra_javascript:
   - javascripts/mathjax.js

docs/en/mathematics/set-theory/relations.md

@@ -63,7 +63,7 @@ Some relations have special properties
 
 ??? note "*Proof*:"
 
-    Suppose $b \in [a]_R$, therefore $aRb$. If $c \in [b]_R$, then $bRc$ and as $aRb$ there is transitivity $aRc$. In particular $[b]_R \subseteq [a]_R$. By symmetry of $R$, $aRb \implies bRa$ and hence $a \in [b]_R$, obtaining $[a]_R \subseteq [b]_R. 
+    Suppose $b \in [a]_R$, therefore $aRb$. If $c \in [b]_R$, then $bRc$ and as $aRb$ there is transitivity $aRc$. In particular $[b]_R \subseteq [a]_R$. By symmetry of $R$, $aRb \implies bRa$ and hence $a \in [b]_R$, obtaining $[a]_R \subseteq [b]_R$. 
 
 <br>
 

docs/stylesheets/extra.css

@@ -0,0 +1,5 @@
+blockquote {
+    background-color: #f0f0f0;
+    opacity: 0.8;
+    color: #333;
+}