TargetUnits in BarLegend

Question

Is there any way to get the '%' in the BarLegend to be black instead of light gray?

ContourPlot[x^2 + y^2, {x, -10, 10}, {y, -10, 10}, 
PlotLegends -> BarLegend[Automatic, LegendFunction -> "Panel",
   LabelStyle -> {FontFamily -> "Monaco", FontSize -> 18, 
   FontColor -> Black}],
FrameStyle -> Black,
TargetUnits -> "%"]

Answer 1

cp = ContourPlot[x^2 + y^2, {x, -10, 10}, {y, -10, 10},
 PlotLegends -> BarLegend[Automatic, LegendFunction -> "Panel",
 LabelStyle -> {FontFamily -> "Monaco", FontSize -> 18,
 FontColor -> Black}], FrameStyle -> Black, TargetUnits -> "%"]

FullForm[cp[[2,1]]] gives the code that constructs the legend. Inspecting that code we find the piece that we need to modify:

Rule[Charting`TickAnnotations, Style[QuantityForm["Percent", "PlotLabel"], GrayLevel[0.7`]]]

So using the following replacement rule

graytoblack = Rule[Charting`TickAnnotations, Style[q_,GrayLevel[_]]]:>
    Rule[Charting`TickAnnotations,   Style[q,GrayLevel[0]]];

to post-process cp

cp/.graytoblack

we get: