refactor: smooth answer appearance

frontend/src/index.css

@@ -514,3 +514,29 @@ input:-webkit-autofill:focus {
 .logs-table {
   font-family: 'IBMPlexMono-Medium', system-ui;
 }
+
+.fade-in {
+  animation: fadeIn 0.5s ease-in-out;
+}
+
+@keyframes fadeIn {
+  0% {
+    opacity: 0;
+  }
+  100% {
+    opacity: 1;
+  }
+}
+
+.fade-in-bubble {
+  opacity: 0;
+  transform: translateY(10px);
+  animation: fadeInUp 0.5s forwards;
+}
+
+@keyframes fadeInUp {
+  to {
+    opacity: 1;
+    transform: translateY(0);
+  }
+}