Create layout.md

layout/layout.md

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+---
+title: Layout
+layout: default
+nav_order: 4.5
+has_children: true
+---
+
+# Layout
+
+You specify the layout for a page in its [front matter]. Just the Docs has a `default` layout with a sidebar, used for almost all pages in the theme docs, and a `minimal` layout that omits the sidebar.
+{: .fs-6 .fw-300 }
+
+## The layout concept
+
+See the [Jekyll docs page about layouts] for an explanation of the general idea of layouts and how to specify them.
+
+You can use [Jekyll's front matter defaults] to specify the same layout for many pages.
+
+## The `default` layout
+
+This page uses the default layout.
+
+It is a *responsive* layout: on medium and larger width displays, it displays a sidebar, including a navigation panel; on smaller width displays, the sidebar is automatically hidden under a button.
+
+Each child (and grandchild) page of a top-level page has so-called *breadcrumbs*: links to its parent (and grandparent) pages. It shows the breadcrumbs above the main content of the page.
+
+Each page that has child pages generally has a list of links to those pages (you can suppress it by `has_toc: false` in the front matter). It shows the list as a *table of contents* below the main content.
+
+## The `minimal` layout
+
+A child and grandchild page of this page use the minimal layout. This differs from the default layout by omitting the sidebar---and thereby also the navigation panel. To navigate between pages with the minimal layout, you can use the breadcrumbs and the tables of contents.
+
+## Selectively hiding or showing the sidebar
+
+[Jekyll's front matter defaults] can be used to apply the `minimal` layout for many pages. But there are also other variables that can control the page layout. In `_config.yml`, you can set `nav_enabled: false` to disable the sidebar navigation panel across the entire site. This can then be selectively enabled on a page-by-page basis by assigning the `nav_enabled: true` page [front matter] variable. For instance, this could be used to enable sidebar navigation on a home page while all other pages have sidebar navigation disabled.
+
+```yaml
+---
+layout: default
+title: Home
+nav_enabled: true
+---
+
+```
+
+## Other layouts
+
+Just the Docs has further layouts: `about`, `home`, `page`, and `post`. Currently, they are all based on the `default` layout. See the [Jekyll docs about inheritance] for how to customize them.
+
+[front matter]: https://jekyllrb.com/docs/front-matter/ "Jekyll docs about front matter"
+[Jekyll docs page about layouts]: https://jekyllrb.com/docs/layouts/ "Jekyll docs about layouts"
+[Jekyll's front matter defaults]: https://jekyllrb.com/docs/configuration/front-matter-defaults/ "Jekyll docs about front matter defaults"
+[Jekyll docs about inheritance]: https://jekyllrb.com/docs/layouts/#inheritance "Jekyll docs about inheritance"