How to change the audio style

[AndersonFirmino]

I've been trying to change the audio style for a few days.

I would like to tinker with the color and how it behaves, I needed to know which event triggers that greenish transform in the corner.

image below:

I would like to know which event triggers this green corner css.
I searched the javascript files and didn't find it and I would like at least one direction on how I can change its color. I looked at the site's documentation but it's not intuitive to find. I ask for help.

Do I need to find where I change the color of the event and where it fires on which line, file?
I need this setting to be for all users in the room.