diff --git a/host_vars/musicdolphin.yml b/host_vars/musicdolphin.yml
index bcf819f..008a9a6 100644
--- a/host_vars/musicdolphin.yml
+++ b/host_vars/musicdolphin.yml
@@ -17,7 +17,3 @@ mediapi_install_kidsmusic: true
 mediapi_has_monitor: true
 musicmouse_version: deploy/musicdolphin
 
-# The attached screen reads back 0 bytes of EDID on both micro-HDMI ports and reports
-# "disconnected", so the kernel offers no modes and X dies with "no screens found".
-# Force the mode instead. Use the port nearest the USB-C jack (HDMI0 = HDMI-A-1).
-pi_kiosk_force_mode: "HDMI-A-1:1920x1080@60e"
diff --git a/roles/pi_kiosk/defaults/main.yml b/roles/pi_kiosk/defaults/main.yml
index 1fc62bd..750db2b 100644
--- a/roles/pi_kiosk/defaults/main.yml
+++ b/roles/pi_kiosk/defaults/main.yml
@@ -1,14 +1,3 @@
 ---
 pi_kiosk_user: "kiosk"
 pi_kiosk_url: "http://localhost:8080"
-
-# Force a mode on the kiosk output, as a `video=` kernel parameter, e.g.
-# "HDMI-A-1:1920x1080@60e" (the trailing `e` forces the output enabled). Empty means
-# "let EDID decide", which is what you want whenever EDID can be read.
-#
-# This is for a display the Pi cannot see: a micro-HDMI cable or adapter whose DDC/HPD
-# lines are broken but whose video pairs are fine reads back 0 bytes of EDID and
-# reports "disconnected", while displaying perfectly once a mode is forced. Note
-# hdmi_force_hotplug=1 does nothing here - it is ignored by the vc4-kms-v3d driver
-# these images use.
-pi_kiosk_force_mode: ""
diff --git a/roles/pi_kiosk/handlers/main.yml b/roles/pi_kiosk/handlers/main.yml
index a08305a..6ed99e1 100644
--- a/roles/pi_kiosk/handlers/main.yml
+++ b/roles/pi_kiosk/handlers/main.yml
@@ -4,9 +4,3 @@
     name: "getty@tty1"
     state: restarted
     daemon_reload: "yes"
-
-- name: Warn that a reboot is needed
-  ansible.builtin.debug:
-    msg: >-
-      /boot/firmware/cmdline.txt changed - the forced display mode only takes effect
-      after a reboot.
diff --git a/roles/pi_kiosk/tasks/main.yml b/roles/pi_kiosk/tasks/main.yml
index 6e748b2..097c299 100644
--- a/roles/pi_kiosk/tasks/main.yml
+++ b/roles/pi_kiosk/tasks/main.yml
@@ -16,6 +16,23 @@
     shell: /bin/bash
     create_home: true
 
+- name: Own the directories X and Firefox write into
+  # Xorg runs as root here (Debian's wrapper, allowed_users=console) with HOME set to
+  # the kiosk user's, so it creates ~/.cache itself - root-owned and 0700 - the first
+  # time it writes a mesa shader cache. Firefox then cannot create ~/.cache/mozilla and
+  # gives up with "Your Firefox profile cannot be loaded. It may be missing or
+  # inaccessible". Creating these up front, owned by the user, means root only ever
+  # adds subdirectories to a directory the user already owns.
+  ansible.builtin.file:
+    path: "/home/{{ pi_kiosk_user }}/{{ item }}"
+    state: directory
+    owner: "{{ pi_kiosk_user }}"
+    group: "{{ pi_kiosk_user }}"
+    mode: "0700"
+  loop:
+    - .cache
+    - .mozilla
+
 - name: Autologin the kiosk user on tty1
   ansible.builtin.file:
     path: /etc/systemd/system/getty@tty1.service.d
@@ -68,23 +85,3 @@
     src: policies.json
     dest: /etc/firefox-esr/policies.json
     mode: "0644"
-
-- name: Read the current kernel command line
-  ansible.builtin.slurp:
-    src: /boot/firmware/cmdline.txt
-  register: pi_kiosk_cmdline
-  when: pi_kiosk_force_mode | length > 0
-
-- name: Force a mode on the kiosk output
-  # cmdline.txt is a single line of space-separated parameters. Rebuild it by dropping
-  # any video= we set before and appending the current one, so changing the mode
-  # replaces it rather than stacking a second one.
-  ansible.builtin.copy:
-    dest: /boot/firmware/cmdline.txt
-    content: >-
-      {{ ((pi_kiosk_cmdline.content | b64decode).split()
-          | reject('match', '^video=') | list
-          + ['video=' ~ pi_kiosk_force_mode]) | join(' ') }}
-    mode: "0755"
-  when: pi_kiosk_force_mode | length > 0
-  notify: Warn that a reboot is needed