bellend.html

<div id="bellend" class="bellend hidden">STOP THAT</div>

<style>
    .hidden {
        display:none;
    }
    .bellend {
        background: #000;
        color: #FFF;
        height: 100%;
        left: 0;
        position: fixed;
        top: 0;
        width: 100%;
        z-index: 2014;

        font-size: 5rem;
        text-align: center;
        padding-top: 15%;
    }
</style>
<script type="text/javascript" charset="utf-8">
/* This WAS jquery.wanker by Mig Reyes - http://mig.io/makes/wanker/
 * Their copyright, MIT license
 *
 * Modified by Matt to work without jQuery
 */
document.addEventListener('DOMContentLoaded', function() {
    var settings = {
        delay: 2000,
        duration: 250
    };

    var message, elapsed, fired, mobile, reset, start, timer;
    message = document.getElementById('bellend');
    mobile = /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent);
    if (!mobile) {

        fired = false;
        start = null;
        elapsed = null;
        timer = null;
        reset = function() {
            fired = false;
            return elapsed = null;
        };

        return window.addEventListener('resize', function() {
            if (fired) {
                elapsed = Math.abs(new Date() - start);
            } else {
                start = new Date();
                fired = true;
            }

            if (elapsed > settings.delay) {
                message.classList.remove('hidden');
            }

            if (timer) {
                clearTimeout(timer);
            }

            return timer = setTimeout(function() {
                message.classList.add('hidden');
                return reset();
            }, settings.duration);
        });
    }
});
</script>