The function isSafeURL in looks at the URI scheme. The scheme is everyting that comes before the colon “:” rune. If the scheme isn’t one of { http, https, mailto } then the URL is not considered safe and ZgotmplZ is printed.

I was trying to render some file:///filename.html links and they were not rendering when using hugo. You can fix this by using the safeURL filter:

<link rel="stylesheet" href="{{"css/my.css" | absURL | safeURL}}" type="text/css">