diff --git a/frontend/src/styles/test.scss b/frontend/src/styles/test.scss
index 9b5e95772..39266e57a 100644
--- a/frontend/src/styles/test.scss
+++ b/frontend/src/styles/test.scss
@@ -562,6 +562,8 @@
           padding: 0.1rem 0.5rem;
           white-space: nowrap;
           line-height: 0.75rem;
+          display: grid;
+          place-content: center center;
         }
         .box:nth-child(1) {
           background: var(--colorful-error-color);
diff --git a/frontend/src/ts/test/test-ui.ts b/frontend/src/ts/test/test-ui.ts
index 34d378dfc..588240f78 100644
--- a/frontend/src/ts/test/test-ui.ts
+++ b/frontend/src/ts/test/test-ui.ts
@@ -891,7 +891,9 @@ export function applyBurstHeatmap(): void {
         }`;
       }
 
-      $("#resultWordsHistory .heatmapLegend .box" + index).text(string);
+      $("#resultWordsHistory .heatmapLegend .box" + index).html(
+        `<div>${string}</div>`
+      );
     });
 
     $("#resultWordsHistory .words .word").each((_, word) => {