Control Master Volume of Jitsi

I’m using the Jitsi Iframe API and I would need to control the “master” volume of the iframe like setting jitsi to volume=0.5 or to volume=0.0
I thought about setting the volume of the div but unfortunately that doesn’t work like it works with audio or video tags.
I followed the thread about controlling the remote track volume of participants but this is too complicated for my application because I don’t need just to control one volume of a participant, I need to control the master volume of the jitsi application

Is there an easy way of achieving this? Would be great if someone could point me into the right direction

thanks, egj