diff --git a/changelog.d/13493.misc b/changelog.d/13493.misc
new file mode 100644
index 0000000000..d7d5c33a89
--- /dev/null
+++ b/changelog.d/13493.misc
@@ -0,0 +1 @@
+Modify HTML template content to better support mobile devices' screen sizes.
\ No newline at end of file
diff --git a/synapse/res/templates/account_previously_renewed.html b/synapse/res/templates/account_previously_renewed.html
index b751359bdf..bd4f7cea97 100644
--- a/synapse/res/templates/account_previously_renewed.html
+++ b/synapse/res/templates/account_previously_renewed.html
@@ -1 +1,12 @@
-
Your account is valid until {{ expiration_ts|format_ts("%d-%m-%Y") }}.
+
+
+
+
+
+
+ Your account is valid until {{ expiration_ts|format_ts("%d-%m-%Y") }}.
+
+
+ Your account is valid until {{ expiration_ts|format_ts("%d-%m-%Y") }}.
+
+
\ No newline at end of file
diff --git a/synapse/res/templates/account_renewed.html b/synapse/res/templates/account_renewed.html
index e8c0f52f05..57b319f375 100644
--- a/synapse/res/templates/account_renewed.html
+++ b/synapse/res/templates/account_renewed.html
@@ -1 +1,12 @@
-Your account has been successfully renewed and is valid until {{ expiration_ts|format_ts("%d-%m-%Y") }}.
+
+
+
+
+
+
+ Your account has been successfully renewed and is valid until {{ expiration_ts|format_ts("%d-%m-%Y") }}.
+
+
+ Your account has been successfully renewed and is valid until {{ expiration_ts|format_ts("%d-%m-%Y") }}.
+
+
\ No newline at end of file
diff --git a/synapse/res/templates/add_threepid.html b/synapse/res/templates/add_threepid.html
index cc4ab07e09..71f2215b7a 100644
--- a/synapse/res/templates/add_threepid.html
+++ b/synapse/res/templates/add_threepid.html
@@ -1,9 +1,14 @@
-
+
+
+
+
+
+
+ Request to add an email address to your Matrix account
+
A request to add an email address to your Matrix account has been received. If this was you, please click the link below to confirm adding this email: