Transparent pinned octotree only transparent if I change --ghd-bg-color

[ghost]

I would like to be able do the following

I used these modifications to make octotree sidebar transparent:

.octotree-views, .octotree-sidebar .octotree-bottom {
    background: #18181800 !important; /* 100% transparent */
}

.octotree-sidebar {
    background: #1818183b !important; /* the used color with 65% transparent */
}

It worked in the past but with recently update, it only works with auto hide sidebar. For pinned side bar, look like there is some magic that adds an extra layer of background to it. But I can't find where the layer is in firefox devtool. Interestingly, when I changed --ghd-bg-color to 100% transparent, it work fine.

Can I make the sidebar transparent without modify --ghd-bg-color? Solution to using a post script with tampermonkey is fine, but I don't know what need to be modified.

Additional context

Firefox Developer 84.0b8

[silverwind]

I've automated the octotree styles, it should generally cover it more completely now in terms of styling. I realize this might make your work of customizing it harder, but at least we're following their styles now so there should not be any additional backgrounds introduced by us.

I guess we could make those background variables configurable, but if we do so, it'd affect the whole site, not just octotree and I guess you probably still want parts of the site opaque.

[ghost]

Yes, I only need the side menu transparent.