In r-lib/pkgdown: Make Static HTML Documentation for a Package

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This vignette teaches you how to customise the style/design of your pkgdown site. We'll start by discussing two techniques that only require tweaks to your _pkgdown.yml: theming (colours and fonts) and layout (content of the navbar, sidebar, footer, ...). We'll then discuss how to add additional HTML and other files. Next, we'll discuss how to give multiple sites the same style using a package, then finish up with some workflow advice.

library(pkgdown)

Getting started

Most theming features work only with Bootstrap 5, so first update your site by adding the following lines to your _pkgdown.yml:

template:
  bootstrap: 5

Overall, the site should look pretty similar, but you will notice a number of small improvements. Most importantly, the default font is much bigger, making it considerably easier to read. Upgrading to Bootstrap 5 has a low chance of breaking your site unless you were using your own pkgdown templates or custom CSS.

Theming

There are two ways to change the visual style of your site from _pkgdown.yml: using a pre-packaged bootswatch theme or customising theme variables with bslib. The following sections show you how.

Bootswatch themes

The easiest way to change the entire appearance of your website is to use a Bootswatch theme:

template:
  bootstrap: 5
  bootswatch: materia

Changing the bootswatch theme affects both the HTML (via the navbar, more on that below) and the CSS, so you'll need to re-build your complete site with build_site() to fully appreciate the changes. While you're experimenting, you can speed things up by just rebuilding the home page and the CSS by running build_home_index(); init_site() (and then refreshing the browser).

Bootswatch templates with tall navbars (e.g. lux, pulse) also require that you set the pkgdown-nav-height bslib variable. Because Bootswatch themes are provided by the bslib R package, you can also nest the bootswatch field under the bslib field.

template:
  bootstrap: 5
  bslib:
    bootswatch: lux
    pkgdown-nav-height: 100px

You can find the correct height by running $(".navbar").outerHeight() in the javascript console.

bslib variables

Instead of picking a complete theme, you can tweak fonts and colours individually using bslib variables. bslib is an R package that wraps sass, the tool that Boostrap uses to produce CSS from a special language called scss. The primary advantage of scss over CSS is that it's more programmable, so you can have a few key bslib variables that affect appearance of many HTML elements.

There are three key variables that affect the colour:

• bg (background) determines the page background.
• fg (foreground) determines the text colour. bg and fg are mixed to yield gray-100, gray-200, ..., grey-900, which are used to style other elements to match the overall colour scheme.
• primary sets the link colour and the (translucent) hover colour in the navbar and sidebar.

template:
  bootstrap: 5
  bslib:
    bg: "#202123"
    fg: "#B8BCC2"
    primary: "#306cc9"

You can customise other components by setting more specific bslib variables, taking advantage of inheritance where possible. For example, table-border-color defaults to border-color which defaults to gray-300. If you want to change the colour of all borders, you can set border-color; if you just want to change the colour of table borders, you can set table-border-color. You can find a full list of variables in vignette("bs5-variables", package = "bslib").

Theming with bslib is powered by bslib::bs_theme() and the bslib field is a direct translation of the arguments to that function. As a result, you can fully specify a bslib theme using the template.bslib field, making it easy to share YAML with the output.html_document.theme field of an R Markdown document.

template:
  bslib:
    version: 5
    bg: "#202123"
    fg: "#B8BCC2"
    primary: "#306cc9"

While iterating on colours and other variables you only need to rerun init_site() and refresh your browser to see the changes.

Fonts

You can also override the default fonts used for the majority of the text (base_font), for headings (heading_font) and for code (code_font). The easiest way is to supply the name of a Google font with the following syntax:

template:
  bootstrap: 5
  bslib:
    base_font: {google: "Roboto"}
    heading_font: {google: "Roboto Slab"}
    code_font: {google: "JetBrains Mono"}

If you want to use a non-Google font, you'll need to do a bit more work. There are two steps: you need to first configure the font with CSS and then use it in your _pkgdown.yml. There are two ways you might get the CSS:

• As a block of CSS which you should put in pkgdown/extra.scss or pkgdown/extra.css. The CSS will look something like this:

  css @font-face { font-family: "proxima-nova"; src: local("Proxima Nova Regular"), local("ProximaNova-Regular"), url("https://example.com/ProximaNova-Regular.eot?#iefix") format("embedded-opentype"), url("https://example.com/fonts/proxima/ProximaNova-Regular.woff2") format("woff2"), url("https://example.com/fonts/proxima/ProximaNova-Regular.woff") format("woff"), url("https://example.com/fonts/proxima/ProximaNova-Regular.ttf") format("truetype"); font-weight: normal; font-style: normal; font-display: fallback; }

• As a link to a style file, which you'll need to add to the <head> using this syntax:

  yaml template: includes: in_header: <link rel="stylesheet" type="text/css" href="https://..." />

Then in _pkgdown.yml you can use the name of the font you just specified:

template:
  bslib:
    base_font: proxima-nova

Depending on where the font is from (and if you paid money for it), you may need to take additional steps to ensure that it can only be used from your site, and/or make sure that it can still be used when you're previewing locally. If you're having problems getting a custom font to work, looking for errors in the browser developer console is a good place to start.

When iterating on fonts, you'll need to run build_home_index(); init_site() then refresh you browser to see the update.

Syntax highlighting

The colours used for syntax highlighting in code blocks are controlled by the theme setting:

template:
  bootstrap: 5
  theme: breeze-light

You can choose from any of the following options: r paste0(pkgdown:::highlight_styles(), collapse = ", ").

Bootswatch themes with a dark background (e.g. cyborg, darkly, solar) will need a dark syntax highlighting theme, e.g. arrow-dark:

template:
  bootstrap: 5
  bootswatch: cyborg
  theme: arrow-dark

The foreground and background colours used for inline code are controlled by code-color and code-bg bslib variables. If you want inline code to match code blocks, you'll need to override the variables yourself, e.g.:

template: 
  bootstrap: 5
  theme: arrow-dark  
  bslib:
    code-bg: "#2b2b2b"

Navbar style

The primary navbar colours are determined by HTML classes, not CSS, and can be customized using the navbar fields bg and type which control the background and foreground colours respectively. Typically bg will be one of light, dark, or primary:

navbar:
  bg: primary

You generally don't need to set bg if you use a bootswatch theme, as pkgdown will pick the bg used on the Bootstwatch preview. Similarly, you don't usually need to set type because bootstrap will guess it for you. If it guesses wrong, override with type: light or type: dark depending on whether the background colour is light (so you need dark text) or type: dark if the background is dark (so you need light text). Unfortunately, these are defined relative to the page background, so if you have a dark site you'll need to flip light and dark (a little experimentation should quickly determine what looks best).

Because the navbar is styled with HTML, you'll need to build_home_index(); init_site() to see the effect of changing this parameter.

Layout {#layout}

You can customise the contents of the navbar, footer, using the navbar and footer fields. See ?build_home for how to customise the sidebar on the homepage. They all use a similar structure that separately defines the overall structure and the individual components.

Navbar {#navbar-heading}

You can customise the navigation bar that appears at the top of the page with the navbar field. It's made up of two pieces: structure, which defines the overall layout, and components, which defines what each piece looks like. This organisation makes it easy to mix and match pkgdown defaults with your own customisations.

This is the default structure:

navbar:
  structure:
    left:  [intro, reference, articles, tutorials, news]
    right: [search, github]

It makes use of the the six built-in components:

• intro: "Get Started", which links to a vignette or article with the same name as the package[^dots].
• reference, if there are any .Rd files.
• articles, if there are any vignettes or articles.
• tutorials, if there any tutorials.
• news, if NEWS.md exists.
• search, the search box (see vignette("search") for more details).
• github, a link to the source repository (with an icon), if it can be automatically determined from the DESCRIPTION.

[^dots]: Note that dots (.) in the package name need to be replaced by hyphens (-) in the vignette filename to be recognized as the intro. That means for a package foo.bar the intro needs to be named foo-bar.Rmd.

You can use the structure field to reorganise the navbar without changing the default contents:

navbar:
  structure:
    left:  [search]
    right: [reference, articles]

You can use components to override the default content. For example, this yaml provides a custom articles menu:

navbar:
 components:
   articles:
    text: Articles
    menu:
    - text: Category A
    - text: Title A1
      href: articles/a1.html
    - text: Title A2
      href: articles/a2.html
    - text: -------
    - text: "Category B"
    - text: Article B1
      href: articles/b1.html

Components uses the same syntax as RMarkdown menus. The elements of menu can be:

• A link (text + href)

• A heading (just text)

• A separator (text: ——–)

Instead of text, you can also use the name of an icons from fontawesome. You should also provide a textual description in the aria-label field for screenreader users.

To add a new component to the navbar, you need to modify both structure and components. For example, the following yaml adds a new "twitter" component that appears to the left of the github icon.

navbar:
  structure:
    right: [twitter, github]
  components:
    twitter:
      icon: fa-twitter
      href: http://twitter.com/hadleywickham
      aria-label: Twitter

Finally, you can add arbitrary HTML to three locations in the navbar:

template:
  includes:
    before_title: <!-- inserted before the package title in the header ->
    before_navbar: <!-- inserted before the navbar links -->
    after_navbar: <!-- inserted after the navbar links -->

These includes will appear on all screen sizes, and will not be collapsed into the the navbar drop down.

You can also customise the colour scheme of the navbar by using the type and bg parameters. See above for details.

Footer

You can customise the footer with the footer field. It's made up of two pieces: structure, which defines the overall layout, and components, which defines what each piece looks like. This organisation makes it easy to mix and match the pkgdown defaults with your own customisations.

This is the default structure:

footer:
  structure: 
    left: developed_by
    right: built_with

Which uses two of the three built-in components:

• developed_by, a sentence describing the main authors of the package. (See ?build_home if you want to tweak which authors appear in the footer.)
• built_with, a sentence advertising pkgdown.
• package, the name of the package.

You can override these defaults with the footer field. The example below puts the authors' information on the right along with a legal disclaimer, and puts the pkgdown link on the left.

footer:
  structure: 
    left: pkgdown
    right: [developed_by, legal]
  components:
    legal: Provided without **any warranty**.

Each side is pasted into a single string (separated by " ") and then converted from markdown to HTML.

Additional HTML and files

If you need to include additional HTML, you can add it in the following locations:

template:
  includes:
    in_header: <!-- inserted at the end of the head -->
    before_body: <!-- inserted at the beginning of the body -->
    after_body: <!-- inserted at the end of the body -->
    before_title: <!-- inserted before the package title in the header ->
    before_navbar: <!-- inserted before the navbar links -->
    after_navbar: <!-- inserted after the navbar links -->

You can include additional files by putting them in the right place:

• pkgdown/extra.css and pkgdown/extra.js will be copied in to rendered site and linked from <head> (after the pkgdown defaults).

• pkgdown/extra.scss will be added to the scss ruleset used to generate the site CSS.

• Any files in pkgdown/assets will be copied to the website root directory.

• For expert users: template files in pkgdown/templates will override layout templates provided by pkgdown or template packages.

Use init_site() to update your rendered website after making changes to these files.

Template packages {#template-packages}

To share a pkgdown style across several packages, the best workflow is to create... a package! It can contain any of the following:

• A configuration file in inst/pkgdown/_pkgdown.yml. This can be used to set (e.g.) author definitions, Bootstrap version and variables, the sidebar, footer, navbar, etc.
• Templates in inst/pkgdown/templates/ will override the default templates.
• Assets in inst/pkgdown/assets/ will be copied in to the destination directory. (Note these files are only copied; you'll need to reference them in your stylesheet or elsewhere in order for them to be actually used.)
• inst/pkgdown/extra.scss will be added to the bslib ruleset. (Note that extra.css is not supported in templates.)

The pkgdown defaults will be overriden by these template files, which are in turn overridden by package specific settings.

Once you have created your template package theverybest, you need to set it as your site's theme:

template:
  package: theverybest

You then also need to make sure it's available when your site is build. Typically, you won't want to publish this package to CRAN, but you will want to publish to GitHub. Once you've done that, and assuming you're using the usethis workflow, add the following line to your DESCRIPTION:

Config/Needs/website: myorg/theverybest

This will ensure that the GitHub action will automatically install it from GitHub when building your pkgdown site.

To get some sense of how a theming package works, you can look at:

• tidytemplate used for tidyverse and tidymodels packages;
• quillt used for R Markdown packages;
• rotemplate used for rOpenSci packages.

But please note that these templates aren't suitable for use with your own package as they're all designed to give a common visual identity to a specific family of packages.

Porting a template package

If you are updating a template package that works with pkgdown 1.0.0, create directories inst/pkgdown/BS5/templates and inst/pkgdown/BS5/assets (if you don't have any templates/assets make sure to a add dummy file to ensure that git tracks them). The templates and assets directories directly under inst/pkgdown will be used by pkgdown 1.0.0 and by pkgdown 2.0.0 if boostrap: 3. The directories under inst/pkgdown/BS5/ will be used for pkgdown 2.0.0 with boostrap: 5. This lets your package support both versions of bootstrap and pkgdown.

PR previews

Lastly, it might be useful for you to get a preview of the website in internal pull requests. For that, you could use Netlify and GitHub Actions (or apply a similar logic to your toolset):

• Create a new Netlify website (either from scratch by dragging and dropping a simple index.html, or by creating a site from a GitHub repository and then unlinking that repository); from the site settings get its ID to be saved as NETLIFY_SITE_ID in your repo secrets; from your account developer settings get a token to be saved as NETLIFY_AUTH_TOKEN in your repo secrets.
• Starting from the standard pkgdown workflow usethis::use_github_action("pkgdown"), add some logic to build the site and deploy it to Netlify for pull requests from inside the repository, not pull requests from forks. Example workflow.

Conclusion

In this vignette we explained how to change the theming and layout of pkgdown websites. Further work to improve user experience will involve:

• Working on the article (?build_articles) and reference indexes (?build_reference).
• Writing a compelling README that explains why your package is so cool/useful/fun.
• Improving the contents of the individual articles and reference topics 😉.

r-lib/pkgdown documentation built on May 1, 2024, 9:15 a.m.