Centered the "Loading..." text. Fixes microsoft#1156

Author: RishabhKothaari

preview-src/app.tsx

@@ -19,5 +19,5 @@ export function Root({ children }) {
 		setPR(ctx.pr);
 	}, []);
 	ctx.postMessage({ command: 'pr.debug', args: ('initialized ' + (pr ? 'with PR' : 'without PR'))});
-	return pr ? children(pr) : 'Loading...';
+	return pr ? children(pr) : <div className='loading-indicator'>Loading...</div>;
 }

preview-src/index.css

@@ -45,6 +45,13 @@ a:focus, input:focus, select:focus, textarea:focus, .title-text:focus {
 	margin-left: 5px;
 }
 
+.loading-indicator{
+	position: fixed;
+	top: 50%;
+	left: 40%;
+	transform: translate(-50%,-50%);
+}
+
 .comment-body li div {
 	display: inline;
 }