style: Add CSS styling for chat messages and buttons

- Style message containers with border, padding, and rounded corners
- Add light gray background color (#f9f9f9) to messages
- Add spacing between message elements with margin-right
- Style buttons with blue background (#007bff) and white text
- Add cursor pointer and rounded corners to buttons
- Improve visual presentation of chat interface

Author: Iswanna

chat-app/frontend/styles.css

@@ -0,0 +1,20 @@
+#all-messages div {
+  border: 1px solid #ccc;
+  padding: 10px;
+  margin: 10px 0;
+  border-radius: 8px;
+  background-color: #f9f9f9;
+}
+
+#all-messages span {
+  margin-right: 10px;
+}
+
+button {
+  cursor: pointer;
+  background-color: #007bff;
+  color: white;
+  border: none;
+  border-radius: 4px;
+  padding: 5px 10px;
+}