Individualize element color

In preparation for adding more track color options

config.js

@@ -0,0 +1,15 @@
+'use strict';
+
+export const gradeColors = {
+    grade_flat: '#fff',
+    grade_0: '#f4f7cd',
+    grade_1: '#f8ff99',
+    grade_2: '#edfc1b',
+    grade_3: '#fcb520',
+    grade_4: '#f07837',
+    grade_5: '#e66441',
+    grade_6: '#ce3f57',
+    grade_7: '#c33577',
+    grade_8: '#a3008d',
+    grade_9: '#690097',
+}