improved coexistence with the dark themes.

[bo-ku-ra]

e.g.

vars: {
  d2-config: {
    theme-overrides: {
    }
    dark-theme-overrides: {
    }
  }
}

classes: {
  RED: {style.font-color: red; style.stroke: red; style.fill: white}
  BLUE: {style.font-color: blue; style.stroke: blue; style.fill: white}
}

dark-classes: {
  #overrides
  RED: {style.font-color: white; style.stroke: red; style.fill: red}
}

a{class: RED}  <-- warm: style.font-color: red / dark: style.font-color: white
b{class: BLUE} <-- warm/dark:  style.font-color: blue; style.stroke: blue; style.fill: white