Bootstrap mobile nav not toggling : <p>Website in question</p>

<p><a href="https://steve-morris.co.uk/" rel="nofollow">https://steve-morris.co.uk/</a></p>

<p>Menu works fine in normal view but when trying to view via a mobile device the nav bar toggle button does  nothing with no errors reported either.</p>

<p>Any ideas?</p>
