const over var

Shogi.UI/wwwroot/index.html

@@ -6,7 +6,7 @@
 	<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" />
 	<title>Shogi.UI</title>
 	<script type="text/javascript">
-		var base = document.createElement('base');
+		const base = document.createElement('base');
 		base.href = window.location.href.includes("localhost")
 			? "/"
 			: "/shogi/";