Set UI color on chrome mobile

packages/master/web/index.html

@@ -3,6 +3,7 @@
   <head>
     <meta charset="utf-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <meta name="theme-color" content="#2a2a2a" />
     <title>Clusterio</title>
     <script>
         window.webRoot = new URL("__WEB_ROOT__", document.location).pathname;