OK!!! This is the missing piece. I see a bit of the vertical scrollbar but I’m sure that’s due to the HA ‘top bar’ and once removed it will be exactly how it should. I thought that the min-height: 100dvh would account for that but I guess not.
I’m going to gdo a little more styling and try and add the graphic over the temperature but that should wrap this one up. I’ve learned a lot with this simple card and appreciate all the help given here and in the Discord channel.