reduce card header font size

Author: medyo

src/App.css

@@ -231,7 +231,7 @@ a {
   color: var(--card-header-text-color);
   font-weight: 400;
   height: 30px;
-  font-size: 18px;
+  font-size: 16px;
   padding-top: 16px;
   padding-bottom: 16px;
   cursor: pointer;