Thema

> 🎨 Semantic themes for use with Stencila encoda.

• Quick Start
• Themes
  • Current themes
  • Structure of themes
• Web Components
• Extensions
  • Current extensions
  • Use an extension
  • Develop an extension
• Develop
  • Prerequisites
  • Getting started
    • Gallery UI parameters
  • Creating a new theme
    • Scripted creation
    • Manual creation
    • Approaches
  • Generated code
  • Testing
    • DOM traversal and manipulation
    • Visual regressions
  • Committing
• Acknowledgments
• Utilities API
  • Functions
  • ready(func)
  • first([elem], selector) ⇒ Element | null
  • select([elem], selector) ⇒ Array.<Element>
  • create([spec], [attributes], ...children) ⇒ Element
  • tag(target, [value]) ⇒ string | Element
  • attrs(target, [attributes]) ⇒ object | undefined
  • attr(target, name, [value]) ⇒ string | null
  • text(target, [value]) ⇒ string | null | undefined
  • append(target, ...elems)
  • prepend(target, ...elems)
  • before(target, ...elems)
  • after(target, ...elems)
  • replace(target, ...elems)
  • wrap(target, elem)

Quick Start

npm install @stencila/thema

/* myStyleSheet.css */
@import '@stencila/thema/dist/themes/stencila/styles.css';

/* myJavaScript.js */
@import '@stencila/thema/dist/themes/stencila';

Themes

Thema comes with several premade themes. Preview and customize the themes in the gallery, or learn how to make one from scratch.

Current themes

Name	Description
bootstrap	A theme that pulls itself up using Twitter's Bootstrap toolkit.
elife	A theme for the journal eLife.
f1000	A theme for the journal F1000Research.
galleria	A theme for galleries of CreativeWork nodes.
giga	A theme for the "Giga" journals GigaScience and GigaByte.
latex	Inspired by the look of traditional scientific manuscripts witten using LaTeX. This theme uses LatexCSS developed by David Zollikofer.
nature	A theme for the journal Nature.
plos	A theme for the journal PLoS.
rpng	A theme for reproducible PNGs (rPNGs). This theme is used in Encoda when generating rPNGs.
skeleton	A theme with lots of bones but no flesh. Designed to be used as a starting point for creating new themes, it tries to be as unopinionated as possible.
stencila	A theme reflecting Stencila's brand and design system. It is based on the Skeleton theme, and demonstrates how to customize a theme using CSS variables.
tufte	A theme inspired by the books and handouts of Edward Tufte. It is based on the Tufte CSS project created by Dave Liepmann.
wilmore	A theme well suited for consuming long-form manuscripts and prose. Named after Edmond Dantés' alias, “Lord Wilmore: An Englishman, and the persona in which Dantès performs random acts of generosity.“

Structure of themes

There are two primary files inside each theme folder. The naming convention of these two files is important, and they must not be changed since they are referred to from encoda.

• styles.css: CSS and visual styles specific to the theme. We use PostCSS to compile the CSS. This is done to utilize PostCSS utilities such as autoprefixing vendor flags to selectors, and writing nested selectors.
• index.ts: Written in TypeScript, this file is loaded asynchronously. It is used to progressively enhance the theme with things like syntax highlighting of code blocks.

Web Components

Stencila Web Components are used to provide interactivity and enhancement to several document nodes.

Encoda will output several Schema nodes as custom HTML elements. Currently, the following node types have Web Components:

Node type	Custom element
CodeChunk	``
CodeExpression	``

More components will be added over time. In the meantime, the "pseudo-component" folders in src/extensions, provide styling for some other node types. See the Extensions section for more details.

Extensions

Extensions provide styling, and potentially interactivity, for node types that do not yet have corresponding web components. They are like fledgling web components, each with it's own CSS (and/or Javascript), that you can import into your own theme. Over time we expect extensions to be promoted to the Stencila components library, thereby obviating the need to import them explicitly.

Current extensions

Name	Description
cite	Provides styling for in-text citations (i.e. Cite and CiteGroup nodes) and bibliographies (i.e. CreativeWork nodes in the references property of another CreativeWork).
cite-apa	Provides styling for in-text citations and bibliographies in accordance with the American Psychological Association (APA) style.
cite-author-year	CSS styles to support author-year in-text citations as used in citation styles such as APA, Chicago and MLA.
cite-mla	Provides styling for in-text citations and bibliographies in accordance with the Modern Language Association (MLA) style.
cite-numeric	CSS styles to support numeric in-text citations (e.g. Vancouver, IEEE citation styles).
code	Provides syntax highlighting for CodeFragment and CodeBlock nodes using Prism. Will not style executable node types like CodeExpression and CodeChunk which are styled by the base Stencila Web Components.
math	Provides styling of math nodes using MathJax fonts and styles. Use this if there is any likely to be math content, i.e. MathFragment and/or MathBlock nodes, in documents that your theme targets.
organization	Provides styling of Organization nodes e.g the authors of an article, or affiliations for each author in it's authors list.
pages	Provides a @media print CSS at-rule to modify properties when printing a document e.g. to PDF.
person	Provides styling of Person nodes e.g the authors of an article, or authors for each citation in it's references.

Use an extension

To add an extension to your theme, you simply have to import it's CSS and Javascript.

First import it's styles.css file into your theme's styles.css file e.g.

@import '../../extensions/cite-apa/styles.css';

Then, if it has one, import it's index.ts file into your theme's index.ts file e.g.

import '../../extensions/cite-apa'

Develop an extension

The first question to ask when developing a new extension is: should I? Extensions are best suited for styling / features that are:

• likely to be used in several themes, and
• needed in a hurry

If it's not likely to be used in more than one or two themes then it's probably not worth creating an extension. If it's not needed in a hurry, then it is probably better to put the effort into contributing a web component to @stencila/components. Having said that, if you are more comfortable writing a simple extension here, to try out some ideas for something that may become a fully fledged web component, we are grateful for any contributions.

The easiest way to create a new extension is using:

npm run create:extension -- myextensionname

That will update the src/extensions/index.ts file with a new entry for your extension and create a new folder in the src/extensions folder with the necessary files:

src/extensions/myext
├── README.md
└── styles.css

You can create the folder and files yourself if you prefer. Just remember to run npm run update:extensions afterwards to add your extension to the index. See the other extensions for approaches to writing the CSS and Javascript / Typescript for your extension.

Some extensions perform manipulation of the DOM to make it more amenable to achieving a particular CSS styling e.g. adding a wrapping <div>s. For performance reasons these manipulations should be kept to a minimum. In some cases, it may be better to make the necessary changes to Encoda's HTML codec. In those cases the DOM manipulations in the extension should be commented as being temporary, and be linked to an issue in Encoda to make those changes permanent.

Develop

Prerequisites

• node
• npm
• git

Getting started

The best way to get started is to develop CSS and JS for a theme with the live updating demo running.

# Clone this repository
git clone git@github.com:stencila/thema.git
cd thema

# Install dependencies
npm install

# Build auto-generated files necessary for theme functionality and development
npm run bootstrap

# Run the development server
npm run dev

Your browser should automatically open (https://localhost:8081)[https://localhost:8081] with the theme gallery view. Any changes to the stylesheets and code will be automatically recompiled and reflected in the browser.

Gallery UI parameters

There are a few URL query parameters which can be used to control the UI of the theme preview.

Parameter	Default Value	Description
theme	stencila	Sets the active theme for the preview
example	articleKitchenSink	Sets the content for the preview
ui	true	When set to false hides the header and theme customization sidebar from the preview page
header	true	When set to false hides only the header from the preview page
sidebar	true	When set to false hides only the theme customization sidebar from the preview page

Creating a new theme

Scripted creation

The easiest way to create a new theme is:

npm run create:theme -- mytheme

Theme names should be all lower case, and start with a letter. This creates a new folder in src/themes and the following files:

• a README.md providing a description of the theme and notes for contributors,
• a styles.css file for the theme's CSS,
• a index.ts for any Typescript that the theme may need

Manual creation

You can create this folder structure for your theme manually. If you prefer to use Javascript instead of Typescript, use a index.js file instead of index.ts. Then update the list of themes in themes/themes.ts and elsewhere using:

npm run update:themes

Approaches

There are three broad approaches to developing a new theme, each epitomized in three of the themes in this repository:

• the skeleton approach: define all styles yourself, importing only the extensions needed for the theme
• the stencila approach: leverage skeleton theme as a foundation, overriding CSS variables and nodes as needed start from a relatively
• the bootstrap approach: reuse existing stylesheets from elsewhere by creating a mapping between Thema's semantic selectors and existing selectors in those stylesheets

It is important to note that the skeleton and bootstrap themes are extremes of each of the approaches - they apply their approach to all document node types. Depending on your theme, the best approach is probably some combination of these approaches for different node types e.g. starting from scratch for some nodes and using shared styles for others.

There are a few key rules enforced by Stylelint:

• All selectors must be descendants of a custom semantic selector. This reduces risks of a theme interfering with exsitng stylesheets on a website.
• Avoid hard-coded values for things such as font-sizes, colors, and fonts. Instead, use CSS variables, as these will allow simple theme overrides within the browser without having to rebuild the theme.
• Design your themes using a mobile-first approach, adding overrides to refine styles on larger screens. At the same time, it is highly recommended to also include print media overrides with your theme.
• These themes are primarily intended for rendering interactive articles and other relatively long forms of prose. As such, good typography is paramount. Reading Matthew Butterick’s Typography in Ten Minutes will give you a solid foundation and a reference for crafting your own themes.

To tweak or adjust an existing theme, you may override some common CSS variables found in the themes. Please refer to the specific theme documentation for available variables.

Type selectors

For types defined by Schema.org (e.g. Article), or extensions such as, schema.stenci.la (e.g. CodeChunk), Bioschemas (e.g. Taxon) etc.

Conventions:

• use the same upper camel case as in the schema the type is defined in
• use a [itemtype=...] selector if possible (i.e. if Encoda encodes it in HTML)

Property selectors

For properties of types defined in schemas.

Conventions:

• use the same lower camel case as in the schema the property is defined in
• use a [itemprop=...] selector for singular properties, or items of container properties

There are several additional selectors which are not found as the Stencila Schema definitions. These are:

Selector	Description	Target
:--root	Used in place of the :root CSS pseudo selector. It maps to the root element generated by Encoda. This is done to avoid potential clashes with external stylesheets, and to ensure that Thema only styles semantically annotated content.	[data-itemscope=root]
:--CodeBlockTypes	Block level code elements	:--CodeBlock, :--CodeChunk
:--CodeTypes	Inline level code elements	:--CodeBlock, :--CodeChunk, :--Code, :--CodeError, :--CodeExpression, :--CodeFragment, :--SoftwareSourceCode
:--ListTypes	List elements, both ordered and unordered, as well as other lists such as author affiliations and article references	:--Article:--root > :--affiliations, :--Collection, :--List, :--references > ol
:--MediaTypes	These are elements which usually benefit from taking up a wider screen area. Elements such as images, video elements, code blocks	:--CodeBlock, :--CodeChunk, :--Datatable, :--Figure, :--ImageObject, :--MediaObject, :--Table, :--VideoObject

Generated code

Some files in the src directory are auto-generated and should not be edited manually. Generated files include:

• src/themes/themes.ts: from the list of sub-folders in the themes folder
• src/examples/examples.ts: from the functions defined in generate/examples.ts
• src/examples/*: files generated by those functions, usually using the @stencila/encoda package
• src/selectors.css: custom selectors from the JSON Schema in the @stencila/schema package

Run npm run update when you add new themes, addons, or examples, or upgrade one of those upstream packages. In particular, when Encoda is upgraded it is important to regenerate HTML for the examples - npm run update is called after npm install to ensure this.

Testing

DOM traversal and manipulation

Authors of themes and extensions, and contributors to the utility functions are encouraged to add tests. We use Jest as a testing framework. Jest ships with jsdom which simulates a DOM environment in Node.js, thereby allowing testing as though running in the browser. See existing *.test.ts files for examples of how to do that.

Visual regressions

We use visual regression testing powered by Sauce Labs, Percy, and WebdriverIO.

As part of the continuous integration for this repository, for each push,

1. themes are built on Travis,
2. examples rendered in a browser running on Sauce Labs,
3. screenshots taken and uploaded to Percy.

To run these tests locally, run npm run test. By default Webdriver will try to run the tests using Chrome, but you can switch to Firefox by setting an TEST_BROWSER=firefox environment variable.

When testing locally, there are three screenshot folders to be aware of inside the test/screenshots directory:

• reference: These are the baseline screenshots. To generate them, make sure your Git branch is free of any changes, and run npm test.
• local: These are screenshots generated by Webdriver tests, and will be compared to those found in the reference directory.
• diff: If any discrepancies are found between the reference and local screenshots, the differences will be highlighted and saved to this directory.

There is a pseudo-test in test/screenshot.test.js which can be un-skipped to help with debugging the automated running of tests.

Committing

Commit messages should follow the conventional commits specification. This is useful (but not essential) because commit messages are used to determine the semantic version of releases and to generate the project's CHANGELOG.md. If appropriate, use the sentence case theme name as the scope (to help make both git log and the CHANGELOG more readable). Some examples,

• fix(Wilmore): Fix Code, Math, DataPublished node formatting & styles
• feat(Elife): Use eLife corresponding author envelope icon
• docs(README): Add some notes on testing
• ci(Travis): Fix command to check themes

Acknowledgments

We rely on many tools and services for which we are grateful ❤ to their developers and contributors for all their time and energy.

Tool	Use
	Cross-browser testing platform
	WebDriver test framework for Node.js

Utilities API

Several utility functions are provided in the util module for traversing and manipulating the DOM. These may be useful for theme and extension authors when there is a need to modify the HTML structure of the document (e.g. adding additional purely presentational elements such as social sharing buttons). Caution should be taken to not overly modify the content. Only use these functions for things that are not possible with CSS alone.

Functions

ready(func)

Register a function to be executed when the DOM is fully loaded.

first([elem], selector) ⇒ Element | null

Select the first element matching a CSS selector.

select([elem], selector) ⇒ Array.<Element>

Select all elements matching a CSS selector.

create([spec], [attributes], ...children) ⇒ Element

Create a new element.

tag(target, [value]) ⇒ string | Element

Get or set the tag name of an element.

attrs(target, [attributes]) ⇒ object | undefined

Get or set the attributes of an element

attr(target, name, [value]) ⇒ string | null

Get or set the value of an attribute on an element.

text(target, [value]) ⇒ string | null | undefined

Get or set the text content of an element.

append(target, ...elems)

Append new child elements to an element.

prepend(target, ...elems)

Prepend new child elements to an element.

before(target, ...elems)

Insert new elements before an element.

after(target, ...elems)

Insert new elements after an element.

replace(target, ...elems)

Replace an element with a new element.

wrap(target, elem)

Wrap an element with a new element.

ready(func)

Register a function to be executed when the DOM is fully loaded.

Kind: global function
Detail: Use this to wrap calls to the DOM selection and manipulation functions to be sure that the DOM is ready before working on it.

Param	Type	Description
func	function	Function to register

Example

ready(() => {
  // Use other DOM manipulation functions here
})

first([elem], selector) ⇒ Element | null

Select the first element matching a CSS selector.

Kind: global function
Returns: Element | null - An Element or null if no match
Detail: This function provides a short hand for querySelector but also allowing for the use of semantic selectors. You can use it for the whole document, or scoped to a particular element.

Param	Type	Description
[elem]	Element	The element to query (defaults to the window.document)
selector	string	The selector to match

Example (Select the first element from the document matching selector)

first(':--CodeChunk')

Example (Select the first element within an element matching the selector)

first(elem, ':--author')

select([elem], selector) ⇒ Array.<Element>

Select all elements matching a CSS selector.

Kind: global function
Returns: Array.<Element> - An array of elements
Detail: Provides a short hand for using querySelectorAll but also allowing for the use of semantic selectors. You can use it for the whole document, or scoped to a particular element.

Param	Type	Description
[elem]	Element	The element to query (defaults to the window.document)
selector	string	The selector to match

Example (Select all elements from the document matching selector)

select(':--CodeChunk')

Example (Select all elements within an element matching the selector)

select(elem, ':--author')

create([spec], [attributes], ...children) ⇒ Element

Create a new element.

Kind: global function
Detail: This function allows creation of new elements using either (a) a HTML (or SVG) string (b) a CSS selector like string, or (c) an Element. CSS selectors are a convenient way to create elements with attributes, particularly Microdata elements. They can be prone to syntax errors however. Alternatively, the second argument can be an object of attribute name:value pairs.

Param	Type	Description
[spec]	string | Element	Specification of element to create.
[attributes]	object | undefined | null | boolean | number | string | Element	Attributes for the element.
...children	undefined | null | boolean | number | string | Element	Child nodes to to add as text content or elements.

Example (Create a <figure> with id, class and itemtype attributes)

create('figure #fig1 .fig :--Figure')
// <figure class="fig" id="fig1">
// </figure>

Example (As above but using an object to specify attributes)

create('figure', {
  id: 'fig1',
  class: 'fig',
  itemscope: '',
  itemtype: translate(':--Figure')
})

Example (Create a Person with a name property)

create(':--Person', create('span :--name', 'John Doe'))
// <div>
//   <span>John Doe</span>
// </div>

Example (Create a link around an SVG image)

create('a', {href: 'https://example.com'}, create(imageSVG))
// <a href="https://example.com">
//   <svg viewBox="0 0 24 24" xmlns="https://www.w3.org/2000/svg"><path d="....
// </a>

<a name=">

tag(target, [value]) ⇒ string | Element

Get or set the tag name of an element.

Kind: global function
Returns: string | Element - The lowercase tag name when getting, a new element when setting.
Detail: Caution must be used when setting the tag. This function does not actually change the tag of the element (that is not possible) but instead returns a new Element that is a clone of the original apart from having the new tag name. Use the replace function where necessary in association with this function.

Param	Type	Description
target	Element	The element to get or set the tag
[value]	string	The value of the tag (when setting)

Example (Get the tag name as a lowercase string)

tag(elem) // "h3"

Example (Setting the tag actually returns a new element)

tag(tag(elem, 'h2')) // "h2"

Example (Change the tag name of an element)

replace(elem, tag(elem, 'h2'))

attrs(target, [attributes]) ⇒ object | undefined

Get or set the attributes of an element

Kind: global function
Returns: object | undefined - The attributes of the element when getting, undefined when setting

Param	Type	Description
target	Element	The element to get or set the attributes
[attributes]	object	The name/value pairs of the attributes

attr(target, name, [value]) ⇒ string | null

Get or set the value of an attribute on an element.

Kind: global function
Returns: string | null - a string if the attribute exists, null if does not exist, or when setting

Param	Type	Description
target	Element	The element to get or set the attribute
name	string	The name of the attribute
[value]	string	The value of the attribute (when setting)

Example (Set an attribute value)

attr(elem, "attr", "value")

Example (Get an attribute)

attr(elem, "attr") // "value"

text(target, [value]) ⇒ string | null | undefined

Get or set the text content of an element.

Kind: global function
Returns: string | null | undefined - null if there is no text content, undefined when setting

Param	Type	Description
target	Element	The element to get or set the text content
[value]	string	The value of the text content (when setting)

Example (Set the text content)

text(elem, "text content")

Example (Get the text content)

text(elem) // "text content"

append(target, ...elems)

Append new child elements to an element.

Kind: global function

Param	Type	Description
target	Element	The element to append to
...elems	Element	The elements to append

prepend(target, ...elems)

Prepend new child elements to an element.

Kind: global function
Detail: When called with multiple elements to prepend will maintain the order of those elements (at the top of the target element).

Param	Type	Description
target	Element	The element to prepend to
...elems	Element	The elements to prepend

before(target, ...elems)

Insert new elements before an element.

Kind: global function

Param	Type	Description
target	Element	The element before which the elements are to be inserted
...elems	Element	The elements to insert

after(target, ...elems)

Insert new elements after an element.

Kind: global function

Param	Type	Description
target	Element	The element after which the elements are to be inserted
...elems	Element	The elements to insert

replace(target, ...elems)

Replace an element with a new element.

Kind: global function

Param	Type	Description
target	Element	The element to replace
...elems	Element	The elements to replace it with

wrap(target, elem)

Wrap an element with a new element.

Kind: global function
Detail: This function can be useful if you need to create a container element to more easily style a type of element.

Param	Description
target	The element to wrap
elem	The element to wrap it in

Example (Wrap all figure captions in a <div>)

select(':--Figure :--caption')
  .forEach(caption => wrap(caption, create('div')))