Developing Themes

A guide to creating and distributing custom themes.

!!! Note

If you are looking for existing third party themes, they are listed in the
MkDocs [community wiki]. If you want to share a theme you create, you
should list it on the Wiki.

When creating a new theme, you can either follow the steps in this guide to create one from scratch or you can download the mkdocs-basic-theme as a basic, yet complete, theme with all the boilerplate required. You can find this base theme on GitHub. It contains detailed comments in the code to describe the different features and their usage.

Creating a custom theme

The bare minimum required for a custom theme is a main.html Jinja2 template file which is placed in a directory that is not a child of the docs_dir. Within mkdocs.yml, set the theme.custom_dir option to the path of the directory containing main.html. The path should be relative to the configuration file. For example, given this example project layout:

mkdocs.yml
docs/
    index.md
    about.md
custom_theme/
    main.html
    ...

... you would include the following settings in mkdocs.yml to use the custom theme directory:

theme:
    name: null
    custom_dir: 'custom_theme/'

!!! Note

Generally, when building your own custom theme, the theme.[name]
configuration setting would be set to `null`. However, if the
theme.[custom_dir] configuration value is used in combination with an
existing theme, the theme.[custom_dir] can be used to replace only specific
parts of a built-in theme. For example, with the above layout and if you set
`name: "mkdocs"` then the `main.html` file in the theme.[custom_dir] would
replace the file of the same name in the `mkdocs` theme but otherwise the
`mkdocs` theme would remain unchanged. This is useful if you want to make
small adjustments to an existing theme.

For more specific information, see [Customizing Your Theme].

!!! Warning

A theme's [configuration] defined in a `mkdocs_theme.yml` file is not loaded
from `theme.custom_dir`. When an entire theme exists in `theme.custom_dir`
and `theme.name` is set to `null`, then the entire theme configuration must
be defined in the [theme] configuration option in the `mkdocs.yml` file.

However, when a theme is [packaged] up for distribution, and loaded using
the `theme.name` configuration option, then a `mkdocs_theme.yml` file
is required for the theme.

Basic theme

The simplest main.html file is the following:

<!DOCTYPE html>
<html>
  <head>
    <title>{% if page.title %}{{ page.title }} - {% endif %}{{ config.site_name }}</title>
  </head>
  <body>
    {{ page.content }}
  </body>
</html>

The body content from each page specified in mkdocs.yml is inserted using the {{ page.content }} tag. Style-sheets and scripts can be brought into this theme as with a normal HTML file. Navbars and tables of contents can also be generated and included automatically, through the nav and toc objects, respectively. If you wish to write your own theme, it is recommended to start with one of the built-in themes and modify it accordingly.

!!! Note

As MkDocs uses [Jinja] as its template engine, you have access to all the
power of Jinja, including [template inheritance]. You may notice that the
themes included with MkDocs make extensive use of template inheritance and
blocks, allowing users to easily override small bits and pieces of the
templates from the theme [custom_dir]. Therefore, the built-in themes are
implemented in a `base.html` file, which `main.html` extends. Although not
required, third party template authors are encouraged to follow a similar
pattern and may want to define the same [blocks] as are used in the built-in
themes for consistency.

Theme Files

There are various files which a theme treats special in some way. Any other files are simply copied from the theme directory to the same path in the site_dir when the site it built. For example image and CSS files have no special significance and are copied as-is. Note, however, that if the user provides a file with the same path in their docs_dir, then the user's file will replace the theme file.

Template Files

Any files with the .html extension are considered to be template files and are not copied from the theme directory or any subdirectories. Also, any files listed in static_templates are treated as templates regardless of their file extension.

Theme Meta Files

The various files required for packaging a theme are also ignored. Specifically, the mkdocs_theme.yml configuration file and any Python files.

Dot Files

Theme authors can explicitly force MkDocs to ignore files by starting a file or directory name with a dot. Any of the following files would be ignored:

.ignored.txt
.ignored/file.txt
foo/.ignored.txt
foo/.ignored/file.txt

Documentation Files

All documentation files are ignored. Specifically, any Markdown files (using any of the file extensions supported by MKDocs). Additionally, any README files which may exist in the theme directories are ignored.

Template Variables

Each template in a theme is built with a template context. These are the variables that are available to themes. The context varies depending on the template that is being built. At the moment templates are either built with the global context or with a page specific context. The global context is used for HTML pages that don't represent an individual Markdown document, for example a 404.html page or search.html.

Global Context

The following variables are available globally on any template.

config

The config variable is an instance of MkDocs' config object generated from the mkdocs.yml config file. While you can use any config option, some commonly used options include:

The nav variable is used to create the navigation for the documentation. The nav object is an iterable of navigation objects as defined by the nav configuration setting.

In addition to the iterable of navigation objects, the nav object contains the following attributes:

The page object for the homepage of the site.

A flat list of all page objects contained in the navigation. This list is not necessarily a complete list of all site pages as it does not contain pages which are not included in the navigation. This list does match the list and order of pages used for all "next page" and "previous page" links. For a list of all pages, use the pages template variable.

Following is a basic usage example which outputs the first and second level navigation as a nested list.

{% if nav|length>1 %}
    <ul>
    {% for nav_item in nav %}
        {% if nav_item.children %}
            <li>{{ nav_item.title }}
                <ul>
                {% for nav_item in nav_item.children %}
                    <li class="{% if nav_item.active%}current{% endif %}">
                        <a href="{{ nav_item.url|url }}">{{ nav_item.title }}</a>
                    </li>
                {% endfor %}
                </ul>
            </li>
        {% else %}
            <li class="{% if nav_item.active%}current{% endif %}">
                <a href="{{ nav_item.url|url }}">{{ nav_item.title }}</a>
            </li>
        {% endif %}
    {% endfor %}
    </ul>
{% endif %}

base_url

The base_url provides a relative path to the root of the MkDocs project. While this can be used directly by prepending it to a local relative URL, it is best to use the url template filter, which is smarter about how it applies base_url.

mkdocs_version

Contains the current MkDocs version.

build_date_utc

A Python datetime object that represents the date and time the documentation was built in UTC. This is useful for showing how recently the documentation was updated.

pages

A flat list of File objects for all pages in the project. This list can contain pages not included in the global navigation and may not match the order of pages within that navigation. The page object for each File can be accessed from file.page.

page

In templates which are not rendered from a Markdown source file, the page variable is None. In templates which are rendered from a Markdown source file, the page variable contains a page object. The same page objects are used as page navigation objects in the global navigation and in the pages template variable.

All page objects contain the following attributes:

page.title

Contains the Title for the current page.

page.content

The rendered Markdown as HTML, this is the contents of the documentation.

page.toc

An iterable object representing the Table of contents for a page. Each item in the toc is an AnchorLink which contains the following attributes:

The following example would display the top two levels of the Table of Contents for a page.

<ul>
{% for toc_item in page.toc %}
    <li><a href="{{ toc_item.url }}">{{ toc_item.title }}</a></li>
    {% for toc_item in toc_item.children %}
        <li><a href="{{ toc_item.url }}">{{ toc_item.title }}</a></li>
    {% endfor %}
{% endfor %}
</ul>
page.meta

A mapping of the metadata included at the top of the markdown page. In this example we define a source property above the page title.

source: generics.py
        mixins.py

# Page title

Content...

A template can access this metadata for the page with the meta.source variable. This could then be used to link to source files related to the documentation page.

{% for filename in page.meta.source %}
  <a class="github" href="https://github.com/.../{{ filename }}">
    <span class="label label-info">{{ filename }}</span>
  </a>
{% endfor %}
page.url

The URL of the page relative to the MkDocs site_dir. It is expected that this be used with the url filter to ensure the URL is relative to the current page.

<a href="{{ page.url|url }}">{{ page.title }}</a>
page.abs_url

The absolute URL of the page from the server root as determined by the value assigned to the site_url configuration setting. The value includes any subdirectory included in the site_url, but not the domain. base_url should not be used with this variable.

For example, if site_url: https://example.com/, then the value of page.abs_url for the page foo.md would be /foo/. However, if site_url: https://example.com/bar/, then the value of page.abs_url for the page foo.md would be /bar/foo/.

page.canonical_url

The full, canonical URL to the current page as determined by the value assigned to the site_url configuration setting. The value includes the domain and any subdirectory included in the site_url. base_url should not be used with this variable.

page.edit_url

The full URL to the source page in the source repository. Typically used to provide a link to edit the source page. base_url should not be used with this variable.

page.is_homepage

Evaluates to True for the homepage of the site and False for all other pages. This can be used in conjunction with other attributes of the page object to alter the behavior. For example, to display a different title on the homepage:

{% if not page.is_homepage %}{{ page.title }} - {% endif %}{{ site_name }}
page.previous_page

The page object for the previous page or None. The value will be None if the current page is the first item in the site navigation or if the current page is not included in the navigation at all. When the value is a page object, the usage is the same as for page.

page.next_page

The page object for the next page or None. The value will be None if the current page is the last item in the site navigation or if the current page is not included in the navigation at all. When the value is a page object, the usage is the same as for page.

page.parent

The immediate parent of the page in the site navigation. None if the page is at the top level.

page.children

Pages do not contain children and the attribute is always None.

page.active

When True, indicates that this page is the currently viewed page. Defaults to False.

page.is_section

Indicates that the navigation object is a "section" object. Always False for page objects.

page.is_page

Indicates that the navigation object is a "page" object. Always True for page objects.

Indicates that the navigation object is a "link" object. Always False for page objects.

Navigation objects contained in the nav template variable may be one of section objects, page objects, and link objects. While section objects may contain nested navigation objects, pages and links do not.

Page objects are the full page object as used for the current page with all of the same attributes available. Section and Link objects contain a subset of those attributes as defined below:

Section

A section navigation object defines a named section in the navigation and contains a list of child navigation objects. Note that sections do not contain URLs and are not links of any kind. However, by default, MkDocs sorts index pages to the top and the first child might be used as the URL for a section if a theme choses to do so.

The following attributes are available on section objects:

section.title

The title of the section.

section.parent

The immediate parent of the section or None if the section is at the top level.

section.children

An iterable of all child navigation objects. Children may include nested sections, pages and links.

section.active

When True, indicates that a child page of this section is the current page and can be used to highlight the section as the currently viewed section. Defaults to False.

section.is_section

Indicates that the navigation object is a "section" object. Always True for section objects.

section.is_page

Indicates that the navigation object is a "page" object. Always False for section objects.

Indicates that the navigation object is a "link" object. Always False for section objects.

A link navigation object contains a link which does not point to an internal MkDocs page. The following attributes are available on link objects:

link.title

The title of the link. This would generally be used as the label of the link.

link.url

The URL that the link points to. The URL should always be an absolute URLs and should not need to have base_url prepened.

link.parent

The immediate parent of the link. None if the link is at the top level.

link.children

Links do not contain children and the attribute is always None.

link.active

External links cannot be "active" and the attribute is always False.

link.is_section

Indicates that the navigation object is a "section" object. Always False for link objects.

link.is_page

Indicates that the navigation object is a "page" object. Always False for link objects.

Indicates that the navigation object is a "link" object. Always True for link objects.

Extra Context

Additional variables can be passed to the template with the extra configuration option. This is a set of key value pairs that can make custom templates far more flexible.

For example, this could be used to include the project version of all pages and a list of links related to the project. This can be achieved with the following extra configuration:

extra:
    version: 0.13.0
    links:
        - https://github.com/mkdocs
        - https://docs.readthedocs.org/en/latest/builds.html#mkdocs
        - https://www.mkdocs.org/

And then displayed with this HTML in the custom theme.

{{ config.extra.version }}

{% if config.extra.links %}
  <ul>
  {% for link in config.extra.links %}
      <li>{{ link }}</li>
  {% endfor %}
  </ul>
{% endif %}

Template Filters

In addition to Jinja's default filters, the following custom filters are available to use in MkDocs templates:

url

Normalizes a URL. Absolute URLs are passed through unaltered. If the URL is relative and the template context includes a page object, then the URL is returned relative to the page object. Otherwise, the URL is returned with base_url prepended.

<a href="{{ page.url|url }}">{{ page.title }}</a>

tojson

Safety convert a Python object to a value in a JavaScript script.

<script>
    var mkdocs_page_name = {{ page.title|tojson|safe }};
</script>

Search and themes

As of MkDocs version 0.17 client side search support has been added to MkDocs via the search plugin. A theme needs to provide a few things for the plugin to work with the theme.

While the search plugin is activated by default, users can disable the plugin and themes should account for this. It is recommended that theme templates wrap search specific markup with a check for the plugin:

{% if 'search' in config['plugins'] %}
    search stuff here...
{% endif %}

At its most basic functionality, the search plugin will simply provide an index file which is no more than a JSON file containing the content of all pages. The theme would need to implement its own search functionality client-side. However, with a few settings and the necessary templates, the plugin can provide a complete functioning client-side search tool based on lunr.js.

The following HTML needs to be added to the theme so that the provided JavaScript is able to properly load the search scripts and make relative links to the search results from the current page.

<script>var base_url = '{{ base_url }}';</script>

With properly configured settings, the following HTML in a template will add a full search implementation to your theme.

<h1 id="search">Search Results</h1>

<form action="search.html">
  <input name="q" id="mkdocs-search-query" type="text" >
</form>

<div id="mkdocs-search-results">
  Sorry, page not found.
</div>

The JavaScript in the plugin works by looking for the specific ID's used in the above HTML. The form input for the user to type the search query must be identified with id="mkdocs-search-query" and the div where the results will be placed must be identified with id="mkdocs-search-results".

The plugin supports the following options being set in the theme's configuration file, mkdocs_theme.yml:

include_search_page

Determines whether the search plugin expects the theme to provide a dedicated search page via a template located at search/search.html.

When include_search_page is set to true, the search template will be built and available at search/search.html. This method is used by the readthedocs theme.

When include_search_page is set to false or not defined, it is expected that the theme provide some other mechanisms for displaying search results. For example, the mkdocs theme displays results on any page via a modal.

search_index_only

Determines whether the search plugin should only generate a search index or a complete search solution.

When search_index_only is set to false, then the search plugin modifies the Jinja environment by adding its own templates directory (with a lower precedence than the theme) and adds its scripts to the extra_javascript config setting.

When search_index_only is set to true or not defined, the search plugin makes no modifications to the Jinja environment. A complete solution using the provided index file is the responsibility of the theme.

The search index is written to a JSON file at search/search_index.json in the site_dir. The JSON object contained within the file may contain up to three objects.

{
    config: {...},
    data: [...],
    index: {...}
}

If present, the config object contains the key/value pairs of config options defined for the plugin in the user's mkdocs.yml config file under plugings.search. The config object was new in MkDocs version 1.0.

The data object contains a list of document objects. Each document object is made up of a location (URL), a title, and text which can be used to create a search index and/or display search results.

If present, the index object contains a pre-built index which offers performance improvements for larger sites. Note that the pre-built index is only created if the user explicitly enables the prebuild_index config option. Themes should expect the index to not be present, but can choose to use the index when it is available. The index object was new in MkDocs version 1.0.

Packaging Themes

MkDocs makes use of Python packaging to distribute themes. This comes with a few requirements.

To see an example of a package containing one theme, see the MkDocs Bootstrap theme and to see a package that contains many themes, see the MkDocs Bootswatch theme.

!!! Note

It is not strictly necessary to package a theme, as the entire theme
can be contained in the `custom_dir`. If you have created a "one-off theme,"
that should be sufficient. However, if you intend to distribute your theme
for others to use, packaging the theme has some advantages. By packaging
your theme, your users can more easily install it, they can rely on a default
[configuration] being defined, and they can then take advantage of the
[custom_dir] to make tweaks to your theme to better suit their needs.

Package Layout

The following layout is recommended for themes. Two files at the top level directory called MANIFEST.in and setup.py beside the theme directory which contains an empty __init__.py file, a theme configuration file (mkdocs-theme.yml), and your template and media files.

.
|-- MANIFEST.in
|-- theme_name
|   |-- __init__.py
|   |-- mkdocs-theme.yml
|   |-- main.html
|   |-- styles.css
`-- setup.py

The MANIFEST.in file should contain the following contents but with theme_name updated and any extra file extensions added to the include.

recursive-include theme_name *.ico *.js *.css *.png *.html *.eot *.svg *.ttf *.woff
recursive-exclude * __pycache__
recursive-exclude * *.py[co]

The setup.py should include the following text with the modifications described below.

from setuptools import setup, find_packages

VERSION = '0.0.1'


setup(
    name="mkdocs-themename",
    version=VERSION,
    url='',
    license='',
    description='',
    author='',
    author_email='',
    packages=find_packages(),
    include_package_data=True,
    entry_points={
        'mkdocs.themes': [
            'themename = theme_name',
        ]
    },
    zip_safe=False
)

Fill in the URL, license, description, author and author email address.

The name should follow the convention mkdocs-themename (like mkdocs- bootstrap and mkdocs-bootswatch), starting with MkDocs, using hyphens to separate words and including the name of your theme.

Most of the rest of the file can be left unedited. The last section we need to change is the entry_points. This is how MkDocs finds the theme(s) you are including in the package. The name on the left is the one that users will use in their mkdocs.yml and the one on the right is the directory containing your theme files.

The directory you created at the start of this section with the main.html file should contain all of the other theme files. The minimum requirement is that it includes a main.html for the theme. It must also include a __init__.py file which should be empty, this file tells Python that the directory is a package.

Theme Configuration

A packaged theme is required to include a configuration file named mkdocs_theme.yml which is placed in the root of your template files. The file should contain default configuration options for the theme. However, if the theme offers no configuration options, the file is still required and can be left blank. A theme which is not packaged does not need a mkdocs_theme.yml file as that file is not loaded from theme.custom_dir.

The theme author is free to define any arbitrary options deemed necessary and those options will be made available in the templates to control behavior. For example, a theme might want to make a sidebar optional and include the following in the mkdocs_theme.yml file:

show_sidebar: true

Then in a template, that config option could be referenced:

{% if config.theme.show_sidebar %}
<div id="sidebar">...</div>
{% endif %}

And the user could override the default in their project's mkdocs.yml config file:

theme:
    name: themename
    show_sidebar: false

In addition to arbitrary options defined by the theme, MkDocs defines a few special options which alters its behavior:

!!! block ""

#### static_templates

This option mirrors the [theme] config option of the same name and allows
some defaults to be set by the theme. Note that while the user can add
templates to this list, the user cannot remove templates included in the
theme's config.

#### extends

Defines a parent theme that this theme inherits from. The value should be
the string name of the parent theme. Normal Jinja inheritance rules apply.

Plugins may also define some options which allow the theme to inform a plugin about which set of plugin options it expects. See the documentation for any plugins you may wish to support in your theme.

Distributing Themes

With the above changes, your theme should now be ready to install. This can be done with pip, using pip install . if you are still in the same directory as the setup.py.

Most Python packages, including MkDocs, are distributed on PyPI. To do this, you should run the following command.

python setup.py register

If you don't have an account setup, you should be prompted to create one.

For a much more detailed guide, see the official Python packaging documentation for Packaging and Distributing Projects.