Increase scroll-bar width on touchscreen kiosk with Chromium browser

Searched on here can’t find the answer… and have tried all sorts of fixes…

Running a touchscreen kiosk with chromium browser powered by a dedicated RPi4. Have nice looking thermostats on the touchscreen to control my radiators… but the scroll bar is way too thin for my fat fingers!

My HA installation is running fine on a RPi5. Using ios-dark-mode-blue-red theme. Have HACS card-mod installed.

So far have tried:

  • enabling and selecting a custom theme (iOS Dark Mode Blue-Red),
  • adding global scrollbar CSS via card-mod-root,
  • adding targeted shadow-DOM rules (hui-view$, ha-sidebar$, ha-dialog$ etc.),
  • disabling GTK overlay scrolling,
  • applying gtk.css changes, and
  • launching Chromium with/without overlay scrollbar flags in both LXDE autostart and systemd kiosk service…

…but the scrollbar in kiosk mode is still thin!

Any additional suggestions from clever folk than me please!? It seems there’s all manner of – switches and parameters that Chromium allows to modify (colour, shades etc) but nothing about width.