IE8 issue with Twitter Bootstrap 3

I also had to set the following META tag:

<meta http-equiv="X-UA-Compatible" content="IE=edge"> 

You got your CSS from CDN (bootstrapcdn.com) respond.js only works for local files. So try your website on IE8 with a local copy of bootstrap.css. Or read: CDN/X-Domain Setup

Note See also: https://github.com/scottjehl/Respond/pull/206

Update:

Please read: http://getbootstrap.com/getting-started/#support

In addition, Internet Explorer 8 requires the use of respond.js to enable media query support.

See also: https://github.com/scottjehl/Respond

For this reason the basic template contains these lines in the head section:

<!-- 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]-->