diff --git a/21.md b/21.md
index 0559007e..c5d80ed0 100644
--- a/21.md
+++ b/21.md
@@ -43,8 +43,7 @@ Ids and signatures omitted and pubkeys shortened for readability.
 
 [^q1]: https://t.me/nostr_protocol/26059
 
-Rationale
----------
+## Rationale
 
 [NIP-04](04.md) is flawed because its event contents are encrypted, but the metadata around it is not, and by the nature of Nostr as a protocol designed for public communication in general anyone is able to query relays for any event they want -- thus it's possible to anyone to track conversations between any other Nostr users, not _exactly what_ they're saying, but to whom they're chatting and how often.
 
@@ -59,8 +58,7 @@ This NIP, if used in conjunction with relays that are trusted to honor it and no
 [^1]: Not considering, of course, the million other features Telegram offers, that are irrelevant to this document.
 [^2]: Not considering, of course, the cryptographic protocols that Signal uses to provide forward secrecy and other advanced functionality which are already not present in NIP-04.
 
-Comparison with other proposals
--------------------------------
+## Comparison with other proposals
 
 Over the last months a number of other proposals were made to try to improve the lack of privacy NIP-04 provides[^3][^4][^5].
 
@@ -75,8 +73,7 @@ Although all these proposals solve the issue in some way of another, and it can
 [^6]: For example, even with ephemeral keys, if the general public still have access to all the events some time-analyses and other heuristics can be used to try to track chat activity between Nostr users.
 [^7]: Another example: even with ephemeral keys, it can be assumed that relays will know at least the IP address of the clients that are using it for the kind-4 messages, so they will have almost as much metadata as before -- which brings us back, again, to some level of trust on these relays to not reveal this metadata to the public, as in the current proposal.
 
-Further possibilities
----------------------
+## Further possibilities
 
 Some random things that can be optionally done based on this NIP: