I have installed HAC in hassio and the instructions for one of the sutom cards states:
When installed, this will be located in ‘/config/www/community/dual-thermostat’ , you still need to add it to your lovelace configuration (‘ui-lovelace.yaml’ or the raw UI config editor) .
In one of your views in Lovelace, click the overflow menu in the upper right (three dots), click Configure UI, click the dots again, then click Raw config editor
@kcd I found this because I was searching for a way to use the dual-gauge-card.js (which hasn’t been updated in four years on GitHub). I have tried putting into the configuration with only the name dual-gauge-card.js, with /www/dual-gauge-card.js, ./www/dual-gauge-card.js and the full path /home/pi/Docker-Compose/Homeassistant/Data/www//dual-gauge-card.js and nothing works. I still get “Custom element doesn’t excist”. The file is there, as taken from the GitHub page, but I can’t understand why I can’t get it into the setup. Would you please shed some light over that, if you can?