Tweak theme

themes/custom-theme/layouts/partials/head/seo.html

@@ -0,0 +1,55 @@
+{{ if eq .Kind "404" }}
+  <meta name="robots" content="noindex, follow" />
+{{ else }}
+  {{ with .Params.robots }}
+    <meta name="robots" content="{{ . }}" />
+  {{ else }}
+    <meta
+      name="robots"
+      content="index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1"
+    />
+  {{ end }}
+{{ end }}
+
+{{ $title := .Title }}
+{{ if .IsHome }}
+  {{ $title = .Site.Title }}
+  {{ with .Site.Params.Subtitle }}
+    {{ $title = printf "%s — %s" $title . }}
+  {{ end }}
+{{ end }}
+<title>{{ $title }}</title>
+
+<meta
+  name="description"
+  content="
+  {{- with .Description -}}
+    {{- . -}}
+  {{- else -}}
+    {{- with .Summary | plainify -}}
+      {{- . -}}
+    {{- else -}}
+      {{- .Site.Params.description -}}
+    {{- end -}}
+  {{- end -}}"
+/>
+
+<link rel="canonical" href="{{ .Permalink }}" />
+
+<!-- Internal Hugo templates -->
+<!-- See https://gohugo.io/templates/internal -->
+{{ template "_internal/twitter_cards.html" . }}
+{{ template "_internal/opengraph.html" . }}
+{{ template "_internal/schema.html" . }}
+
+
+<!-- RSS feed -->
+<!-- See https://gohugo.io/templates/rss/#reference-your-rss-feed-in-head -->
+{{ range .AlternativeOutputFormats }}
+  <link
+    rel="{{ .Rel }}"
+    type="{{ .MediaType.Type }}"
+    href="{{ .RelPermalink }}"
+    title="{{ $.Site.Title }}"
+  />
+{{ end }}