How to set transparency of button card

[gioleuzzi]

Hi,
I built a panel in HA with some button cards for my tablet. I set an image in backround but the cards remain white-coloured.
I would know how to set transparency of such cards in order to see the backround.
Could someone help me?
Tks😉

[SirRhor]

Try this:

color: rgba(0,0,0,0.4)

The 0.4 value controls transparency on the card's background if you use the section that controls the background.
If that does not work, then try to use a theme, but that will affect everything on HA.
I use this one: https://github.com/basnijholt/lovelace-ios-themes