perf: use higher contrast red and blue in dashboard graph gradients

Change-Id: Iea5625f5b143b7f0a806adfdf022ee5347304330
Reviewed-on: https://go-review.googlesource.com/c/build/+/412379
Reviewed-by: Michael Pratt <mpratt@google.com>
diff --git a/third_party/bandchart/bandchart.js b/third_party/bandchart/bandchart.js
index 5369555..9e2ba69 100644
--- a/third_party/bandchart/bandchart.js
+++ b/third_party/bandchart/bandchart.js
@@ -68,11 +68,11 @@
 	const defs = svg.append("defs")
 
 	const maxHalfColorValue = 0.10;
-	const maxHalfColorOpacity = 0.25;
+	const maxHalfColorOpacity = 0.5;
 
 	// Draw top half.
-	const goodColor = "blue";
-	const badColor = "red";
+	const goodColor = "#005AB5";
+	const badColor = "#DC3220";
 
 	// By default, lower is better.
 	var bottomColor = goodColor;