chore: font size changed of cashback modal.

Author: NiloyDas789

frontend-dev/src/resource/css/cashback-modal.css

@@ -5,7 +5,7 @@
   padding: 0px 15px;
   height: 40px;
   background-color: rgb(78, 255, 191);
-  font-size: 20px;
+  font-size: 15px;
   color: #390066;
   font-weight: 700;
   margin-right: 10px;