refactor: remove category colors from units app

components/units/VisualComparison.tsx

@@ -6,13 +6,11 @@ import { formatNumber, cn } from '@/lib/utils';
 
 interface VisualComparisonProps {
   conversions: ConversionResult[];
-  color: string;
   onValueChange?: (value: number, unit: string, dragging: boolean) => void;
 }
 
 export default function VisualComparison({
   conversions,
-  color,
   onValueChange,
 }: VisualComparisonProps) {
   const [draggingUnit, setDraggingUnit] = useState<string | null>(null);
@@ -282,12 +280,11 @@ export default function VisualComparison({
               {/* Colored fill */}
               <div
                 className={cn(
-                  "absolute inset-y-0 left-0",
+                  "absolute inset-y-0 left-0 bg-primary",
                   draggingUnit ? "transition-none" : "transition-all duration-500 ease-out"
                 )}
                 style={{
                   width: `${displayPercentage}%`,
-                  backgroundColor: color,
                 }}
               />
               {/* Percentage label overlay */}