Bootstrap grid with fixed wrapper - Prevent column

As the title says I'm trying to use Bootstrap 3 grid system with a fixed wrapper. But when I resize the Browser the columns stack up even if the wrapper stays the same size?

BTW: I'm using version 3 so that I can move to a responsive layout after I have ported the site. (Which is huge and I'm alone, so step by step is the only option ...)

    <!DOCTYPE html>
    <html>
      <head>
        <title>Bootstrap 101 Template</title>
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <!-- Bootstrap -->
        <link rel="stylesheet" href="http://netdna.bootstrapcdn.com/bootstrap/3.0.0/css/bootstrap.min.css">

        <!-- HTML5 shim and Respond.js IE8 support of HTML5 elements and media queries -->
        <!--[if lt IE 9]>
          <script src="../../assets/js/html5shiv.js"></script>
          <script src="../../assets/js/respond.min.js"></script>
        <![endif]-->

        <style>
                /* Custom container */
                .container-fixed {
                  margin: 0 auto;
                  max-width: 800px;
                  min-width: 800px;
                  width: 800px;
                                      background-color:#C05659;
                }
                .container-fixed > hr {
                  margin: 30px 0;
                }
        </style>
      </head>
      <body>
            <div class="container-fixed">
                <div class="row">
                  <div class="col-md-4">.col-md-4</div>
                  <div class="col-md-4">.col-md-4</div>
                  <div class="col-md-4">.col-md-4</div>
                </div>
                <hr>
            </div>

        <!-- jQuery (necessary for Bootstrap's JavaScript plugins) -->
        <script src="http://code.jquery.com/jquery.min.js"></script>
        <!-- Include all compiled plugins (below), or include individual files as needed -->
        <script src="http://netdna.bootstrapcdn.com/bootstrap/3.0.0/js/bootstrap.min.js"></script>
      </body>
    </html>

The sm,md,lg,etc.. cols wrap/stack responsively. Use the non-stacking col-xs-* class...

<div class="container">
  <div class="row">
    <div class="col-xs-4">.col-4</div>
    <div class="col-xs-4">.col-4</div>
    <div class="col-xs-4">.col-4</div>
  </div>
</div>

Demo: http://bootply.com/80085

EDIT: Bootstrap 4, the xs no longer needs to be specified..

<div class="container-fluid">
  <div class="row">
    <div class="col-4">.col-4</div>
    <div class="col-4">.col-4</div>
    <div class="col-4">.col-4</div>
  </div>
</div>