diff --git a/B04_wf1_Surface/B04_wf1_Surface_UI_MapViewer.ts b/B04_wf1_Surface/B04_wf1_Surface_UI_MapViewer.ts
index 2b8c3bbc..1b1aab8a 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_UI_MapViewer.ts
+++ b/B04_wf1_Surface/B04_wf1_Surface_UI_MapViewer.ts
@@ -360,7 +360,7 @@ export function createSurfaceMapViewer(): SurfaceMapViewer {
     width: number,
     height: number,
   ): void {
-    context.font = "10px sans-serif";
+    context.font = "600 13px sans-serif";
     context.textAlign = "center";
     context.textBaseline = "middle";
     (Object.keys(CONTOUR_LABEL_KEYS) as GisLayer[]).forEach((layer) => {