Add main CSS styles for React build

build/static/css/main.css

@@ -0,0 +1,67 @@
+/* Basic React app styles */
+body {
+  margin: 0;
+  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
+    'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
+    sans-serif;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}
+
+code {
+  font-family: source-code-pro, Menlo, Monaco, Consolas, 'Courier New',
+    monospace;
+}
+
+.App {
+  text-align: center;
+}
+
+.App-logo {
+  height: 40vmin;
+  pointer-events: none;
+}
+
+@media (prefers-reduced-motion: no-preference) {
+  .App-logo {
+    animation: App-logo-spin infinite 20s linear;
+  }
+}
+
+.App-header {
+  background-color: #282c34;
+  padding: 20px;
+  color: white;
+}
+
+.App-link {
+  color: #61dafb;
+}
+
+@keyframes App-logo-spin {
+  from {
+    transform: rotate(0deg);
+  }
+  to {
+    transform: rotate(360deg);
+  }
+}
+
+/* Custom styles for proxy demo */
+.proxy-info {
+  background: #f5f5f5;
+  padding: 20px;
+  border-radius: 8px;
+  margin: 20px auto;
+  max-width: 600px;
+}
+
+.endpoint-list {
+  text-align: left;
+  color: #555;
+}
+
+.endpoint-list li {
+  margin: 10px 0;
+  padding: 5px 0;
+}