diff --git a/book/source/03-cryptography.md b/book/source/03-cryptography.md
index 9f047fd..f79051f 100644
--- a/book/source/03-cryptography.md
+++ b/book/source/03-cryptography.md
@@ -95,9 +95,13 @@ Only the public part of an asymmetric key pair
 
 OpenPGP makes heavy use of public-key cryptography, both for encryption and signing operations.
 
-Note that, for historical reasons, the OpenPGP RFC and other documentation often use the non-standard term "secret key" instead of the more common "private key."
+```{admonition} Terminology
+:class: note
+
+For historical reasons, the OpenPGP RFC and other documentation often use the non-standard term "secret key" instead of the more common "private key."
 
 So in OpenPGP, the pair of terms "public/secret key" is sometimes used instead of the more common "public/private key."
+```
 
 ### Cryptographic digital signatures