- switching from firestore to realtime DB

- implement debouncing tactic to sync data
- display sync indicator

src/styles/global.css

@@ -38,3 +38,13 @@ section {
 #artboard hr {
   border-color: #eee;
 }
+
+.spin {
+  animation: spin 1s linear infinite;
+}
+
+@keyframes spin {
+  100% {
+    transform: rotate(360deg);
+  }
+}