include system color override

Author: andrewseguin

tensorboard/webapp/theme/_tb_theme.template.scss

@@ -49,6 +49,13 @@ $tb-theme: /*m2*/ mat.define-light-theme(
     density: 0,
   )
 );
+$tb-theme: map_set(
+    $tb-theme,
+    color,
+    system,
+    on-surface,
+    /*m2*/ mat.get-color-from-palette(/*m2$*/ mat.$gray-palette, 900)
+);
 
 // Overriding mat-light-theme-foreground variables.
 $tb-foreground: map_merge(