centralize preference feedback message

src/routes/profile/+page.svelte

@@ -205,12 +205,15 @@
     }
 
     .save-message {
-				color: green;
+        color: green;
         height: 2rem;
         overflow: hidden;
         position: relative;
         margin-top: 1rem;
+        text-align: center;
+        display: flex;
+        justify-content: center;
+        align-items: center;
     }
 
-
 </style>