message: demo: make navbar not fixed top
diff: <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css"
  integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
  <link rel="stylesheet" type="text/css" href="demo/styles.css">
  - <style>
  - #my-app {margin-top: 80px;}
  - </style>
  </head>
  <body>
  -
  - <!-- Fixed navbar -->
  - <nav class="navbar navbar-default navbar-fixed-top">
  + <!-- navbar -->
  + <nav class="navbar navbar-default">
  <div class="container">
  <div class="navbar-header">
  <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false" aria-controls="navbar">
  