Add pulsation effect to warning sign

app/src/pages/write-tweet/write-tweet.scss

@@ -36,5 +36,18 @@ page-write-tweet {
   }
   ion-icon.warning {
     color: orange;
+    animation: pulse 1.8s infinite;
+  }
+}
+
+@keyframes pulse {
+  0% {
+    transform: scale(1);
+  }
+  50% {
+    transform: scale(1.3);
+  }
+  100% {
+    transform: scale(1);
   }
 }