Optionalcolor?: stringThe text colour on the selected route's bubble. The deselected routes' bubbles keep their muted text, as their lines keep their grey.
the map's label colour when a theme sets it and the bubble has no SummaryBubblesConfig.color, else black or white, whichever reads on the bubble.
The bubble is the text's background, so the text takes no halo. A title replaces the text
SummaryBubblesConfig.fields builds. A function title is called for each route when the
routes are shown, when another is selected and when the display units change. A route it returns
an empty string for gets no bubble.
The text of the route summary bubbles: its size, colour, opacity, typeface and what it says.