diff --git a/README.md b/README.md
index 393f351..aa4a00d 100644
--- a/README.md
+++ b/README.md
@@ -19,7 +19,7 @@ If you don't have YunoHost, please consult [the guide](https://yunohost.org/#/in
 Akkoma is a microblogging server software that can federate (= exchange messages with) other servers that support ActivityPub. What that means is that you can host a server for yourself or your friends and stay in control of your online identity, but still exchange messages with people on larger decentrilized and federated network. Akkoma will federate with all servers that implement ActivityPub, like Friendica, GNU Social, Hubzilla, Mastodon, Misskey, Pleroma, Peertube, or Pixelfed.
 
 
-**Shipped version:** 3.6.0~ynh1
+**Shipped version:** 3.6.0~ynh2
 
 **Demo:** https://otp.akkoma.dev
 
@@ -43,12 +43,38 @@ Akkoma is a microblogging server software that can federate (= exchange messages
 - **Login fails** for non YNH users if LDAP is activated (this is by default). See [#15](https://github.com/YunoHost-Apps/akkoma_ynh/issues/15) for more explanation.
 - No way to **change user password** from admin interface. May be related to previous bug. Work like charm from CLI.
 
+## Backups
+
+This application uses the [core-only feature of the backup](https://yunohost.org/en/backup/include_exclude_files#do-not-backup-large-amoun). **This means the app data directory** (`/home/yunohost.app/akkoma`, with subfolder `/static/`, which contains terms of service, custom emoji, custom themes, and `/uploads/` which contains the media attachements) **is not saved during backup**.
+Also to keep the integrity of the data and to have a better guarantee of the restoration it is recommended to stop Akkoma during the operation. Proceed as follows:
+- Stop Akkoma service with this command: `service akkoma stop`
+- Launch Akkoma backup with this command: `yunohost backup create --apps akkoma`
+- Backup Akkoma data directory with your specific strategy (could be with rsync, borg backup or just cp). The data is generally stored in `/home/yunohost.app/akkoma`.
+- Restart Akkoma service with this command: `service akkoma start`
+
+**If you want to create a Yunohost backup that contains also Akkoma data directory**, you should add `BACKUP_CORE_ONLY=0` at the start fo the command : `BACKUP_CORE_ONLY=0 yunohost backup create --app akkoma`.
+
+## Remove
+
+Due of the backup core only feature **the data directory in `/home/yunohost.app/akkoma` is not removed**. 
+If you want to delete the data folder `/home/yunohost.app/akkoma/` during removal of akkoma, you should add the `--purge` option. If you don't, it must be manually deleted to purge user data.
+**This is a necessary step for complete removal** - and possibly a fresh install.
+
+*NB: don't forget this mean those data are* not *backed up by default. See above.*
 
 ## Customization
 
 This application come with the default frontend (Pleroma FE) and admin interface pre-installed and activated. There is also the Mangane front-end who is installed but not active. Note that you can choose other _alternative public interfaces_  (Brutaldon, Fedi FE...) or even provide a custom one.
 
-**Mastodon frontend:** if you installed the Mastodon FE package (from CLI or Admin interface) you can have access to an alternate user interface, similar the Mastodons or Glitch frontend. This frontend live alongside the default Pleroma FE: to access just add `/web` at the end of your instance domain (eg. `akkoma.domain.tld/web`). 
+**Mastodon frontend:** if you installed the Mastodon FE package (from CLI or Admin interface) you can have access to an alternate user interface, similar the Mastodons or Glitch frontend. This frontend live alongside the default Pleroma FE: to access just add `/web` at the end of your instance domain (eg. `akkoma.domain.tld/web`).
+
+### Custom theme
+
+You can eitheir create your custom theme or use [existing ones](https://docs.akkoma.dev/stable/configuration/howto_theming_your_instance/#get-an-existing-theme).
+To add custom themes, you will have to upload them to your instance dedicated folder (`/home/yunohost.app/akkoma/static/themes/` in Yunohost case), then to edit `/home/yunohost.app/akkoma/static/styles.json` to add a new entry referencing it. See the [official documentation](https://docs.akkoma.dev/stable/configuration/howto_theming_your_instance/#adding-the-custom-theme-to-the-instance) for more details.
+- Upload your custom theme, place it in `/home/yunohost.app/akkoma/static/themes/` (you could also directly edit the file from the command line and copy-paste the content).
+- Make sure the file access rights are approriate (only akkoma user can access them) `sudo chown -R akkoma:akkoma /home/yunohost.app/akkoma/static/themes/` (= own by akkoma) and `sudo chmod 750 /home/yunohost.app/akkoma/static/themes/` (=only akkoma can read and edit the file).
+- Then edit `/home/yunohost.app/akkoma/static/styles.json` for instance with `sudo su akkoma nano /home/yunohost.app/akkoma/static/styles.json`.
 
 ### Uploaded files size
 By default, the web server [NGINX is configured](https://github.com/YunoHost-Apps/akkoma_ynh/blob/testing/conf/nginx.conf#L12) with a maximum value for uploading files at 50 MB. You can change the value only in akkoma under this limit. To go higher, you also need to change NGINX value on `/etc/nginx/conf.d/my.domain.tld.d/akkoma.conf` : change `client_max_body_size 50M;` value in order to do so.
diff --git a/README_fr.md b/README_fr.md
index bd86a41..a4825e7 100644
--- a/README_fr.md
+++ b/README_fr.md
@@ -19,7 +19,7 @@ Si vous n’avez pas YunoHost, regardez [ici](https://yunohost.org/#/install) po
 Akkoma is a microblogging server software that can federate (= exchange messages with) other servers that support ActivityPub. What that means is that you can host a server for yourself or your friends and stay in control of your online identity, but still exchange messages with people on larger decentrilized and federated network. Akkoma will federate with all servers that implement ActivityPub, like Friendica, GNU Social, Hubzilla, Mastodon, Misskey, Pleroma, Peertube, or Pixelfed.
 
 
-**Version incluse :** 3.6.0~ynh1
+**Version incluse :** 3.6.0~ynh2
 
 **Démo :** https://otp.akkoma.dev
 
@@ -43,12 +43,38 @@ Akkoma is a microblogging server software that can federate (= exchange messages
 - **Login fails** for non YNH users if LDAP is activated (this is by default). See [#15](https://github.com/YunoHost-Apps/akkoma_ynh/issues/15) for more explanation.
 - No way to **change user password** from admin interface. May be related to previous bug. Work like charm from CLI.
 
+## Backups
+
+This application uses the [core-only feature of the backup](https://yunohost.org/en/backup/include_exclude_files#do-not-backup-large-amoun). **This means the app data directory** (`/home/yunohost.app/akkoma`, with subfolder `/static/`, which contains terms of service, custom emoji, custom themes, and `/uploads/` which contains the media attachements) **is not saved during backup**.
+Also to keep the integrity of the data and to have a better guarantee of the restoration it is recommended to stop Akkoma during the operation. Proceed as follows:
+- Stop Akkoma service with this command: `service akkoma stop`
+- Launch Akkoma backup with this command: `yunohost backup create --apps akkoma`
+- Backup Akkoma data directory with your specific strategy (could be with rsync, borg backup or just cp). The data is generally stored in `/home/yunohost.app/akkoma`.
+- Restart Akkoma service with this command: `service akkoma start`
+
+**If you want to create a Yunohost backup that contains also Akkoma data directory**, you should add `BACKUP_CORE_ONLY=0` at the start fo the command : `BACKUP_CORE_ONLY=0 yunohost backup create --app akkoma`.
+
+## Remove
+
+Due of the backup core only feature **the data directory in `/home/yunohost.app/akkoma` is not removed**. 
+If you want to delete the data folder `/home/yunohost.app/akkoma/` during removal of akkoma, you should add the `--purge` option. If you don't, it must be manually deleted to purge user data.
+**This is a necessary step for complete removal** - and possibly a fresh install.
+
+*NB: don't forget this mean those data are* not *backed up by default. See above.*
 
 ## Customization
 
 This application come with the default frontend (Pleroma FE) and admin interface pre-installed and activated. There is also the Mangane front-end who is installed but not active. Note that you can choose other _alternative public interfaces_  (Brutaldon, Fedi FE...) or even provide a custom one.
 
-**Mastodon frontend:** if you installed the Mastodon FE package (from CLI or Admin interface) you can have access to an alternate user interface, similar the Mastodons or Glitch frontend. This frontend live alongside the default Pleroma FE: to access just add `/web` at the end of your instance domain (eg. `akkoma.domain.tld/web`). 
+**Mastodon frontend:** if you installed the Mastodon FE package (from CLI or Admin interface) you can have access to an alternate user interface, similar the Mastodons or Glitch frontend. This frontend live alongside the default Pleroma FE: to access just add `/web` at the end of your instance domain (eg. `akkoma.domain.tld/web`).
+
+### Custom theme
+
+You can eitheir create your custom theme or use [existing ones](https://docs.akkoma.dev/stable/configuration/howto_theming_your_instance/#get-an-existing-theme).
+To add custom themes, you will have to upload them to your instance dedicated folder (`/home/yunohost.app/akkoma/static/themes/` in Yunohost case), then to edit `/home/yunohost.app/akkoma/static/styles.json` to add a new entry referencing it. See the [official documentation](https://docs.akkoma.dev/stable/configuration/howto_theming_your_instance/#adding-the-custom-theme-to-the-instance) for more details.
+- Upload your custom theme, place it in `/home/yunohost.app/akkoma/static/themes/` (you could also directly edit the file from the command line and copy-paste the content).
+- Make sure the file access rights are approriate (only akkoma user can access them) `sudo chown -R akkoma:akkoma /home/yunohost.app/akkoma/static/themes/` (= own by akkoma) and `sudo chmod 750 /home/yunohost.app/akkoma/static/themes/` (=only akkoma can read and edit the file).
+- Then edit `/home/yunohost.app/akkoma/static/styles.json` for instance with `sudo su akkoma nano /home/yunohost.app/akkoma/static/styles.json`.
 
 ### Uploaded files size
 By default, the web server [NGINX is configured](https://github.com/YunoHost-Apps/akkoma_ynh/blob/testing/conf/nginx.conf#L12) with a maximum value for uploading files at 50 MB. You can change the value only in akkoma under this limit. To go higher, you also need to change NGINX value on `/etc/nginx/conf.d/my.domain.tld.d/akkoma.conf` : change `client_max_body_size 50M;` value in order to do so.
diff --git a/conf/styles.json b/conf/styles.json
new file mode 100644
index 0000000..5697694
--- /dev/null
+++ b/conf/styles.json
@@ -0,0 +1,8 @@
+{
+  "pleroma-dark": [ "Pleroma Dark", "#121a24", "#182230", "#b9b9ba", "#d8a070", "#d31014", "#0fa00f", "#0095ff", "#ffa500" ],
+  "pleroma-light": [ "Pleroma Light", "#f2f4f6", "#dbe0e8", "#304055", "#f86f0f", "#d31014", "#0fa00f", "#0095ff", "#ffa500" ],
+  "classic-dark": [ "Classic Dark", "#161c20", "#282e32", "#b9b9b9", "#baaa9c", "#d31014", "#0fa00f", "#0095ff", "#ffa500" ],
+  "bird": [ "Bird", "#f8fafd", "#e6ecf0", "#14171a", "#0084b8", "#e0245e", "#17bf63", "#1b95e0", "#fab81e"],
+  "ir-black": [ "Ir Black", "#000000", "#242422", "#b5b3aa", "#ff6c60", "#FF6C60", "#A8FF60", "#96CBFE", "#FFFFB6" ],
+  "monokai": [ "Monokai", "#272822", "#383830", "#f8f8f2", "#f92672", "#F92672", "#a6e22e", "#66d9ef", "#f4bf75" ],
+}
diff --git a/doc/DISCLAIMER.md b/doc/DISCLAIMER.md
index fbf9fe2..366f5df 100644
--- a/doc/DISCLAIMER.md
+++ b/doc/DISCLAIMER.md
@@ -12,12 +12,38 @@
 - **Login fails** for non YNH users if LDAP is activated (this is by default). See [#15](https://github.com/YunoHost-Apps/akkoma_ynh/issues/15) for more explanation.
 - No way to **change user password** from admin interface. May be related to previous bug. Work like charm from CLI.
 
+## Backups
+
+This application uses the [core-only feature of the backup](https://yunohost.org/en/backup/include_exclude_files#do-not-backup-large-amoun). **This means the app data directory** (`/home/yunohost.app/akkoma`, with subfolder `/static/`, which contains terms of service, custom emoji, custom themes, and `/uploads/` which contains the media attachements) **is not saved during backup**.
+Also to keep the integrity of the data and to have a better guarantee of the restoration it is recommended to stop Akkoma during the operation. Proceed as follows:
+- Stop Akkoma service with this command: `service akkoma stop`
+- Launch Akkoma backup with this command: `yunohost backup create --apps akkoma`
+- Backup Akkoma data directory with your specific strategy (could be with rsync, borg backup or just cp). The data is generally stored in `/home/yunohost.app/akkoma`.
+- Restart Akkoma service with this command: `service akkoma start`
+
+**If you want to create a Yunohost backup that contains also Akkoma data directory**, you should add `BACKUP_CORE_ONLY=0` at the start fo the command : `BACKUP_CORE_ONLY=0 yunohost backup create --app akkoma`.
+
+## Remove
+
+Due of the backup core only feature **the data directory in `/home/yunohost.app/akkoma` is not removed**. 
+If you want to delete the data folder `/home/yunohost.app/akkoma/` during removal of akkoma, you should add the `--purge` option. If you don't, it must be manually deleted to purge user data.
+**This is a necessary step for complete removal** - and possibly a fresh install.
+
+*NB: don't forget this mean those data are* not *backed up by default. See above.*
 
 ## Customization
 
 This application come with the default frontend (Pleroma FE) and admin interface pre-installed and activated. There is also the Mangane front-end who is installed but not active. Note that you can choose other _alternative public interfaces_  (Brutaldon, Fedi FE...) or even provide a custom one.
 
-**Mastodon frontend:** if you installed the Mastodon FE package (from CLI or Admin interface) you can have access to an alternate user interface, similar the Mastodons or Glitch frontend. This frontend live alongside the default Pleroma FE: to access just add `/web` at the end of your instance domain (eg. `akkoma.domain.tld/web`). 
+**Mastodon frontend:** if you installed the Mastodon FE package (from CLI or Admin interface) you can have access to an alternate user interface, similar the Mastodons or Glitch frontend. This frontend live alongside the default Pleroma FE: to access just add `/web` at the end of your instance domain (eg. `akkoma.domain.tld/web`).
+
+### Custom theme
+
+You can eitheir create your custom theme or use [existing ones](https://docs.akkoma.dev/stable/configuration/howto_theming_your_instance/#get-an-existing-theme).
+To add custom themes, you will have to upload them to your instance dedicated folder (`/home/yunohost.app/akkoma/static/themes/` in Yunohost case), then to edit `/home/yunohost.app/akkoma/static/styles.json` to add a new entry referencing it. See the [official documentation](https://docs.akkoma.dev/stable/configuration/howto_theming_your_instance/#adding-the-custom-theme-to-the-instance) for more details.
+- Upload your custom theme, place it in `/home/yunohost.app/akkoma/static/themes/` (you could also directly edit the file from the command line and copy-paste the content).
+- Make sure the file access rights are approriate (only akkoma user can access them) `sudo chown -R akkoma:akkoma /home/yunohost.app/akkoma/static/themes/` (= own by akkoma) and `sudo chmod 750 /home/yunohost.app/akkoma/static/themes/` (=only akkoma can read and edit the file).
+- Then edit `/home/yunohost.app/akkoma/static/styles.json` for instance with `sudo su akkoma nano /home/yunohost.app/akkoma/static/styles.json`.
 
 ### Uploaded files size
 By default, the web server [NGINX is configured](https://github.com/YunoHost-Apps/akkoma_ynh/blob/testing/conf/nginx.conf#L12) with a maximum value for uploading files at 50 MB. You can change the value only in akkoma under this limit. To go higher, you also need to change NGINX value on `/etc/nginx/conf.d/my.domain.tld.d/akkoma.conf` : change `client_max_body_size 50M;` value in order to do so.
diff --git a/manifest.json b/manifest.json
index 14e85b4..ba2e5d1 100644
--- a/manifest.json
+++ b/manifest.json
@@ -6,7 +6,7 @@
         "en": "Federated social networking server built on ActivityPub open protocol",
         "fr": "Serveur de réseautage social fédéré basé sur le protocole ouvert ActivityPub"
     },
-    "version": "3.6.0~ynh1",
+    "version": "3.6.0~ynh2",
     "url": "https://akkoma.social/",
     "upstream": {
         "license": "AGPL-3.0-only",
diff --git a/scripts/backup b/scripts/backup
index 9d07a3b..22831db 100644
--- a/scripts/backup
+++ b/scripts/backup
@@ -48,6 +48,7 @@ ynh_backup --src_path="$final_path"
 # BACKUP THE DATA DIR
 #=================================================
 
+# When using BACKUP_CORE_ONLY (default), this folder will not be saved. This saves a lot of space and time, in particular during upgrades.
 ynh_backup --src_path="$datadir" --is_big
 
 #=================================================
diff --git a/scripts/install b/scripts/install
index b64d5c1..6f59708 100644
--- a/scripts/install
+++ b/scripts/install
@@ -153,6 +153,8 @@ mkdir -p $datadir
 mkdir -p "$datadir/uploads/"
 mkdir -p "$datadir/static/"
 mkdir -p "$datadir/static/emoji/"
+mkdir -p "$datadir/static/static/themes"
+mv ../conf/styles.json "$datadir/static/styles.json"
 
 chmod 750 "$datadir"
 chmod -R o-rwx "$datadir"
diff --git a/scripts/remove b/scripts/remove
index bd52739..c89865f 100644
--- a/scripts/remove
+++ b/scripts/remove
@@ -71,8 +71,10 @@ ynh_secure_remove --file="$final_path"
 # Remove the data directory if --purge option is used
 if [ "${YNH_APP_PURGE:-0}" -eq 1 ]
 then
-	ynh_script_progression --message="Removing app data directory..." --weight=1
+	ynh_script_progression --message="Purge option was selected. Removing app data directory..." --weight=1
 	ynh_secure_remove --file="$datadir"
+else
+	ynh_script_progression --message="Purge option was not selected. App data directory is not removed. That is good if you want to restore a backup. For fresh install, you should remove it first." --weight=1
 fi
 
 #=================================================