MarkdownAlertColors
class MarkdownAlertColors(val note: Color, val tip: Color, val important: Color, val warning: Color, val caution: Color)
The accent colour of each GFM alert kind -- > [!NOTE] through > [!CAUTION].
Drawn as the alert's border and title. These are the one part of the palette that cannot be a tint of the text colour, because an alert's whole meaning is the named hue it carries.