ADA-compliant font colors in RStudio?

The RStudio scripting environment didn't do this yesterday: I thought my keyboard was substituting blanks for equal signs. It's putting them onscreen in pale pale pastel yellow. Other colors, while better visible, are pale and pastel.

I messed with "theme" stuff in the global settings, but the preview behavior did not jar the production side out of its pastel propensities. Perhaps "theme" is the wrong thing.