Make a cables patch background clear, transparent

So I am testing a cables patch to stick into a div, basically I have moved the cables style into my own style sheet ( the relevant “canvas block” style ), I then call the
“” in a nested div to display a cable patch.

What I wondering is, it seems the default background is not clear, I always imagined cables content was drawn over a black background in the editor. When I load it into my div the background is black, is there a way to make the the background clear? Do I do that at the authoring stage of my patch or at the coding stage of my webpage. Another curiosity is the z-index, I’ve some control over it using:

canvas {
display: block;
z-index:1000;
}

I saw a Z-index in the cables js script file, part of the package included when you download your own patch to run on your website. What should we use to control z-index? I know browsers all try to work in order of logical priorities, I’m thinking CSS has the highest priority? that is, if called in the CSS stylesheet. I believe that because the cables .js files has a really hi z-index like 100000 or something and I used 1000 to make the object visible, it was not before that point, so I assume the CSS in web page has priority over the .js in the cables .js script. Sorry my question is so convoluted, to be clear where should we best define z-index when integrating cables with other elements in our websites. btw this is for my own website not a commercial one.

check mainloop options and try to disable clear and clearalpha checkboxes

thanks