Simplify and align detection of remote links

layouts/_partials/docs/links/portable-image.html

@@ -1,7 +1,7 @@
 {{- $destination := .Destination -}}
 {{- $url := urls.Parse .Destination -}}
 
-{{- $isRemote := gt (len $url.Host) 0 -}}
+{{- $isRemote := $url.IsAbs -}}
 {{- $isFragment := strings.HasPrefix .Destination "#" -}}
 
 {{- if and (not $isRemote) (not $isFragment) -}}

layouts/_partials/docs/links/portable-link.html

@@ -1,7 +1,7 @@
 {{- $destination := .Destination -}}
 {{- $url := urls.Parse .Destination -}}
 
-{{- $isRemote := gt (len $url.Host) 0 -}}
+{{- $isRemote := $url.IsAbs -}}
 {{- $isFragment := strings.HasPrefix .Destination "#" -}}
 
 {{- if and (not $isRemote) (not $isFragment) -}}

layouts/_partials/docs/menu-hugo.html

@@ -17,7 +17,7 @@
     {{- $class = $class | append "active" -}}
   {{- end -}}
   <li>
-    {{- $isRemote := not (or (.Page) (strings.HasPrefix .URL "/")) -}}
+    {{- $isRemote := (urls.Parse .URL).IsAbs -}}
     <a href="{{ .URL }}"
       {{- with $class }}class="{{ delimit . " " }}"{{ end -}}
       {{- with .Title }}title="{{ . }}"{{ end -}}

layouts/_shortcodes/button.html

@@ -1,5 +1,5 @@
-{{ $href := partial "docs/links/portable-link" (dict "Page" .Page "Destination" (.Get "href")) -}}
-{{ $isRemote := (urls.Parse $href).Scheme}}
+{{- $href := partial "docs/links/portable-link" (dict "Page" .Page "Destination" (.Get "href")) -}}
+{{- $isRemote := (urls.Parse $href).IsAbs -}}
 <a {{ with $href }}href="{{ $href }}"{{ end }} {{ with $isRemote }}target="_blank" rel="noopener"{{ end }} class="book-btn{{ with .Get "class" }} {{ . }}{{ end }}">
   {{- .InnerDeindent -}}
 </a>