Update app.py

app.py

@@ -21,7 +21,7 @@ body {
 }
 #chat-title {
   color: #856966;
-  font-family: 'Space Mono', serif;
+  font-family: 'Playfair Display', serif;
   font-size: 1.8rem;
   font-weight: bold;
   text-align: center;