Looks like you're using IE11?
Even in IE8 mode, IE11 doesn't respect conditional comments. In particular, this means that it ignores the conditional comment containing the HTML5 element and CSS media query polyfills that Bootstrap advises:
<!-- HTML5 shim and Respond.js IE8 support of HTML5 elements and media queries -->
<!--[if lt IE 9]>
<script src="https://oss.maxcdn.com/libs/html5shiv/3.7.0/html5shiv.js"></script>
<script src="https://oss.maxcdn.com/libs/respond.js/1.4.2/respond.min.js"></script>
<![endif]-->