Add div class to fix layout to bottom tab section

app/views/editions/secondary_nav_tabs/_unpublish.html.erb

@@ -1,28 +1,29 @@
-<%@edition= @resource %>
-<%= header_for("Unpublish") %>
+<div class="govuk-grid-column-two-thirds">
+  <% @edition = @resource %>
+  <%= header_for("Unpublish") %>
 
-<%= render "govuk_publishing_components/components/inset_text", {
-  text: "If you unpublish a page from GOV.UK it cannot be undone."
-} %>
-
-<%= form_for @edition, url: confirm_unpublish_edition_path, method: "get" do |f| %>
-  <%= render "govuk_publishing_components/components/input", {
-    label: {
-      text: "Redirect to URL",
-    },
-    id: "redirect_url",
-    name: "redirect_url",
-    value: params[:redirect_url],
-    hint:"For example: https://www.gov.uk/redirect-to-replacement-page",
-    heading_level: 3,
-    heading_size: "s",
-    error_items: errors_for(f.object.errors,:redirect_url, use_full_message: false)
+  <%= render "govuk_publishing_components/components/inset_text", {
+    text: "If you unpublish a page from GOV.UK it cannot be undone."
   } %>
-  <div class="govuk-button-group">
-    <%= render("govuk_publishing_components/components/button", {
-      text: "Continue",
-      type: "submit",
-    }) %>
-  </div>
-<% end %>
 
+  <%= form_for @edition, url: confirm_unpublish_edition_path, method: "get" do |f| %>
+    <%= render "govuk_publishing_components/components/input", {
+      label: {
+        text: "Redirect to URL",
+      },
+      id: "redirect_url",
+      name: "redirect_url",
+      value: params[:redirect_url],
+      hint: "For example: https://www.gov.uk/redirect-to-replacement-page",
+      heading_level: 3,
+      heading_size: "s",
+      error_items: errors_for(f.object.errors, :redirect_url, use_full_message: false)
+    } %>
+    <div class="govuk-button-group">
+      <%= render("govuk_publishing_components/components/button", {
+        text: "Continue",
+        type: "submit",
+      }) %>
+    </div>
+  <% end %>
+</div>