diff --git a/dev-logs/staging-env.md b/dev-logs/staging-env.md
index 6fb6e2d7..8957208c 100644
--- a/dev-logs/staging-env.md
+++ b/dev-logs/staging-env.md
@@ -20,7 +20,9 @@ The staging environment allows verification of changes in a production-like sett
 
 `localhost` is used to quickly build this environment. Compared to a public endpoint like `staging.my-domain.com`, `localhost` can be tested locally. Otherwise, development would need to be done on a remote machine serving as `staging.my-domain.com`, or frequent `git` operations would be required.
 
-The drawback of using `localhost` is the need to manually install the local CA certificate.
+The drawback of using `localhost` is 
+* the need to manually install the local CA certificate.
+* issue like `Access-Control-Allow-Origin` can only be revealed when using public endpoints.
 
 Once the staging env is stable, a public endpoint like `staging.my-domain.com` should be preferred.
 
diff --git a/playbook/Certificate.md b/playbook/Certificate.md
index ed8db851..51de9a68 100644
--- a/playbook/Certificate.md
+++ b/playbook/Certificate.md
@@ -1,6 +1,7 @@
 # Certificate
+~~san11pk.org use [Let's Encrypt](https://letsencrypt.org/) to generate certificates.~~
 
-san11pk.org use [Let's Encrypt](https://letsencrypt.org/) to generate certificates.
+san11pk.org use Caddy to manage https certificates.
 
 [Detailed instruction](https://certbot.eff.org/instructions?ws=other&os=ubuntufocal)