Make grid layout work on category and taxonomy templates.

layouts/_default/category.html

 {{ define "main" }}
-	<div class="entry-content">
-		<h1>Posts categorised under “{{ .Page.Title }}”</h1>
+	<div class="entry-content content">
+		<h1 class="long-title">Posts categorised under “{{ .Page.Title }}”</h1>
 		{{- .Content -}}
 	</div>
 	{{ $section := .Data.Pages }}

layouts/_default/taxonomy.html

 {{ define "main" }}
-	<div class="entry-content">
-		<h1>Posts tagged with: “{{ .Page.Title }}”</h1>
+	<div class="entry-content content">
+		<h1 class="long-title">Posts tagged with: “{{ .Page.Title }}”</h1>
 		{{- .Content -}}
 	</div>
 	{{ $section := .Data.Pages }}