Mermaid background set to black

[Pshemas]

When in dark mode it seems that mermaid gets it background from var(--joplin-background-color) !important . Which is problematic as it is black and simply does not look good.

I've been able to deal with it partially by adding :

.CodeMirror-sizer .mermaid-chart svg {
    background-color: #FFFFFF;
}

to my custom stylesheet. This makes the background for the image itself white, but the whole div is still black and I can't figure out where it is hardcoded (and sadly I don't see a class / id for this section I could use).

Any suggestions which file I could edit to get rid of this black background styling?