Try to use l3keys.

packages/Color.sty

@@ -7,7 +7,7 @@
 \RequirePackage{xcolor}
 
 \definecolorset{HTML}{Prime}{}{%
-	Gray,	474c63;% #474c63	Blue, saturation -> 17%
+	Gray,	4d505d;% #4d505d	Blue, saturation -> 10%
 	Red,	91192d;% #91192d	Tetradic
 	Orange,	914119;% #914119	Split complementary
 	Yellow,	917d19;% #917d19	Complementary
@@ -22,7 +22,7 @@
 
 % Lightness ≈ 18%
 \definecolorset{HTML}{PrimeDark}{}{%
-	Gray,	262836;% #262836
+	Gray,	292b32;% #292b32
 	Red,	4e0d18;% #4e0d18
 	Orange,	4e230d;% #4e230d
 	Yellow,	4e430d;% #4e430d
@@ -37,7 +37,7 @@
 
 % Lightness ≈ 49%
 \definecolorset{HTML}{PrimeBright}{}{%
-	Gray,	686f91;% #686f91
+	Gray,	727587;% #727587
 	Red,	d42542;% #d42542
 	Orange,	d46025;% #d46025
 	Yellow,	d4b725;% #d4b725
@@ -52,7 +52,7 @@
 
 % Lightness ≈ 64%
 \definecolorset{HTML}{PrimeLight}{}{%
-	Gray,	9499b3;% #9499b3
+	Gray,	9b9eac;% #9b9eac
 	Red,	e46378;% #e46378
 	Orange,	e48f63;% #e48f63
 	Yellow,	e4d063;% #e4d063
@@ -67,7 +67,7 @@
 
 % Lightness ≈ 64%
 \definecolorset{HTML}{PrimePastel}{}{%
-	Gray,	c2c5d4;% #c2c5d4
+	Gray,	c6c8d0;% #c6c8d0
 	Red,	f0a6b2;% #f0a6b2
 	Orange,	f0bfa6;% #f0bfa6
 	Yellow,	f0e4a6;% #f0e4a6
@@ -82,7 +82,7 @@
 
 % Lightness ≈ 95%
 \definecolorset{HTML}{PrimePale}{}{%
-	Gray,	eff0f5;% #eff0f5
+	Gray,	f0f1f4;% #eff0f5
 	Red,	fbe9ec;% #fbe9ec
 	Orange,	fbefe9;% #fbefe9
 	Yellow,	fbf8e9;% #fbf8e9