contrast-color() beyond black & white

Two CSS techniques extend contrast-color() beyond its black-or-white limitation. Method 1 uses color-mix() to blend a brand color into the contrast-color() result, creating tinted variants while maintaining accessibility (10–25% for light, 30–40% for dark backgrounds). Method 2 uses registered custom properties combined with CSS if() or @container style() queries to map the light/dark detection result to fully custom color palettes, giving complete control over foreground colors per background context. Both approaches treat contrast-color() as a light/dark detector and require manual accessibility validation.