Mermaid draws every flowchart label in the theme's text colour, so a
`style` or `classDef` fill can hide it: light text on a pale node in dark
mode, dark text on a deep one in light mode. After rendering, labels that
fall below 4.5:1 on their node's fill switch to whichever theme colour
reads better, on desktop previews, chat and the phone.
Co-authored-by: Nico Hu <haoyu.hu@lexmount.com>
Kelvin AmoabaandNico Hu
3ddaa8df6f