Possible to remove the container GUI?

Hello! I've made my own .png background image with rounded corners to make it look better. But the lightgrey container is ruining it, any way to disable it? Can't seem to find the config for it ():

3fc423886a4e67b168fd40256a27e418.png

 

Try setting this to 0
Thanks alot! Saved me alot of time, got it working now.
Stay safe and wash your hands <Ö>

Merged post

1b1183f502e4b3e71ec0a3aba3dd2830.png

Btw..

Is there any way to make the container background for the kits not looking like a minecraft block aswell with more rounded smooth corners without doing custom photshopped .png files?