www.doublefourteen.io/themes/doublefourteen/layouts/_default/_markup/render-link.html

<a href="{{ .Destination | safeURL }}" {{ with .Title}} title="{{ . }}"{{ end }} {{ $url := urls.Parse (absURL .Destination) }} {{ $website := urls.Parse (absURL "") }} {{ if ne $url.Host $website.Host }} class="external-link" target="_blank" rel="noopener"{{ end }}>{{ .Text | safeHTML }}</a>