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, when the display units or the title itself change
and when the bubbles turn visible again. 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.