message: style: update index.html viewport setting
diff: <!-- The first thing in any HTML file should be the charset -->
  <meta charset="utf-8">
  <!-- Make the page mobile compatible -->
  - <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
  + <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">
  <!-- Allow installing the app to the homescreen -->
  <meta name="mobile-web-app-capable" content="yes">
  