For me the light mode has white on white text.
I use Firefox on Ubuntu. (In Chrome looks as it should.)
The browser may claim, that I prefer dark mode.
But in the preferences I have unchecked "Enable automatic dark mode color scheme".
The offending CSS is:
@media (prefers-color-scheme: dark) {
.topic-body .cooked
{
color: #FFF;
}
}
Also I would suggest not to use dark background for transparent images in dark mode.
Vector graphics often contain black labels, assuming a light background.
This includes the diagrams exported from the neo4j browser: