@financial-times/o-typography v7.6.2

o-typography

Typographical styles for FT branded sites.

• Overview
• Usage
• Markup
• Sass
• JavaScript
• Troubleshooting
• Migration guide
• Contact
• Licence

Overview

The component provides typographical fundamentals such as font scales, vertical rhythm, and font fallbacks. Plus styles for UI including links, headings, and titles.

Other components build on o-typography to provide for more specific usecases such as editorial typography, quotes, or big numbers.

By default, o-typography uses a single typographic scale for use with all fonts. The scale consists of font-size and line-height combinations, as shown below:

Note: The whitelabel branded version of o-typography has a different default scale. The font sizes are the same, but the line-height is 1.2x the font size at every scale.

This scale makes up all typographic styles available through o-typography. It is available when using Sass through the typography mixins.

Usage

Check out how to include Origami components in your project to get started with o-typography.

Markup

Predefined CSS classes in o-typography are available when using the Build Service, and can be included optionally via Sass.

Classes do not depend on specific HTML, but we encourage developers to use semantic elements.

E.g.

<h1 class="o-typography-heading-level-1">Heading level 1</h1>
<h2 class="o-typography-heading-level-2">Heading level 2</h2>
<p class="o-typography-body">Some body copy.</p>
<a class="o-typography-link" href="#" >Some link.</a>
<!-- etc. -->

A link may open in a new window/tab with target="_blank" but we recommend against this for most cases as it may disorientate users (see the Web Content Accessibility Guidelines for advice on when it may be appropriate to open in a new window/tab). Use the rel="noreferrer noopener" attribute with target="_blank" to avoid exploitation of the window.opener API.

<a href="https://www.w3.org/TR/WCAG20-TECHS/G200.html" rel="noreferrer noopener" target="_blank" class="o-typography-link">Some external link.</a>

See the demos for a full list of the classes provided and their effects.

Wrapper Class

o-typography also provides wrapper classes. These reduce the need for developers to apply styles to specific elements. By using a wrapper, body styles get applied to the HTML element and descendent typographic elements: h1, h2, h3, h4, h5, p, a, footer, strong, em, small, sup, sub, ul, ol, li.

Example:

<div class="o-typography-wrapper">
	<h1>Heading level 1</h1>
	<h2>Heading level 2</h2>
	<p>Some body copy.</p>
	<a href="#">Some link.</a>
</div>

See the demos for a full list of the classes provided and their effects.

Theme Class

o-typography also provides wrapper classes for theming.

• o-typography-inverse - Make body copy and links white, for use on a dark background.
• o-typography-professional - Change link colours for the FT Professional sub-brand (core brand only)
• o-typography-professional o-typography-inverse - A version of the inverse theme for use with the FT Professional sub-brand (core brand only)
• o-typography-ft-live o-typography-inverse - A version of the inverse theme for use with the FT Live sub-brand (core brand only)

E.g:

<div class="o-typography-professional">
	<a class="o-typography-link" href="#">Some link using FT Professional branding.</a>
</div>

Progressive Loading Web Fonts

One of the drawbacks of using web fonts is some browsers hide the text while the font is downloading (Flash of Invisible Text, aka FOIT). The font-display property may be used within font faces to show a system font fallback initially. Then either swap immediately when the font has loaded or on the next page load.

However font-display is not supported by Internet Explorer or mobile Safari 10, so o-typography provides a custom implementation which works by removing a class from the html element used to display the fallback font. Using this approach we're able to support older browsers and adjust the size of the fallback font so it looks more similar to our custom font. The CSS would look a little like this:

p {
	font-family: FinancierDisplayWeb, serif;
	font-size: 20px;
	line-height: 24px;
}

.font-loading-serif p {
	font-family: serif;
	font-size: 18px;
}

To remove the need for o-typography's progressive font loading on ft.com, and the fallback font resizing it gives us, may require work across ft.com projects.

Disable Progressive Loading

If you do not want to use o-typography progressive font loading set $o-typography-progressive-font-loading: false; at the top of your project before importing components:

// configure o-typography to not include progressive font fallback css
$o-typography-progressive-font-loading: false;
// import dependencies
@import '@financial-times/o-typography/main';
@import '@financial-times/o-fonts/main';

Setup Progressive Loading

To setup o-typography progressive font loading include both its CSS and JavaScript in your project. While ensuring you have the loading classes for each font you wish to load on your html element:

<html class="o-typography--loading-sans o-typography--loading-sans-bold o-typography--loading-display o-typography--loading-display-bold">

The fallback font will be switched for the custom font on each page load, as o-typography JavaScript detects the font has loaded and removes the above CSS classes. This causes a visual "flash". To prevent that add the following JavaScript snippet in the head of your page:

	var rootElement = document.querySelector('html')
	if (/(^|\s)o-typography-fonts-loaded=1(;|$)/.test(document.cookie)) {
		var fontLabels = ['sans', 'sans-bold', 'display', 'display-bold']
		for (var i = 0; i < fontLabels.length; i++) {
			rootElement.className = rootElement.className.replace('o-typography--loading-' + fontLabels[i], '')
		}
	}

If you build your projects using Sass, styles for progressively loading fonts are output by default when using the use case mixins or type mixins.

Sass

To include all typography classes use the oTypography mixin:

@include oTypography();

To include typography styles granularly pass an options argument with the features to include:

@include oTypography($opts: (
	'wrapper'
));

See the demos for a full list of the CSS classes provided by these features.

Note: Including fonts

Calling oTypography will output font faces to download custom Financial Times fonts. However IE11 may download fonts which are not used. To include font faces more granularly based on your use of o-typography set $o-typography-load-fonts: false and use o-fonts.

// import dependencies
@import '@financial-times/o-typography/main';
@import '@financial-times/o-fonts/main';
// configure o-typography to not include fonts
$o-typography-load-fonts: false;
// include a limited set of recommended font families manually
@include oFonts($opts: ('recommended': true));
// include css for all typography
@include oTypography();

If an oTypography mixin outputs a font family/weight/style for a font face which hasn't been included in the project it is possible to throw an error by setting $o-typography-error-for-missing-fonts to an error message. A custom error message is useful as what the engineer should do depends on the project.

// import dependencies
@import '@financial-times/o-typography/main';
@import '@financial-times/o-fonts/main';
// configure o-typography to not include fonts
$o-typography-load-fonts: false;
// error if a font is used which has not been included
$o-typography-error-for-missing-fonts: 'This project only allows recommended o-fonts! No fun for you without first discussing performance with the Font Guardians of this project.';
// include a limited set of recommended font families manually
@include oFonts($opts: ('recommended': true));
// try to use a font which is not recommended,
// and has not been included with o-fonts
.fancy-typography-used-only-here {
	// throws an error which includes the `$o-typography-error-for-missing-fonts` message.
	// a thin/italic font face has not been included
	@include oTypographySans($scale: 1, $weight: 'thin', $style: 'normal');
}

The Sass in o-typography also provides several mixins for use in your project. To explore all functions/mixins see the SassDoc documentation in the registry.

Use Case Mixins

To avoid duplicated CSS we recommend using default o-typography classes output by oTypography. Where you are unable to use o-typography markup, Sass mixins may be used to output styles for usecases such as headings, body copy, and links.

See o-typography SassDoc for a full list of mixins including more details and examples. Also see editorial typography, quotes, and big numbers for more specific typography usecases.

oTypographyHeading

Use oTypographyHeading to output styles for heading levels 1-6.

h2 {
	@include oTypographyHeading($level: 2);
}

oTypographyBody

Use oTypographyBody to output styles for body copy such as paragraph text.

p {
	@include oTypographyBody();
}

You may also output body styles for use on a dark background using the inverse theme:

p {
	@include oTypographyBody($theme: 'inverse');
}

oTypographyLink

Use oTypographyLink to output styles for links.

a {
	@include oTypographyLink();
}

You may also output link styles for a given theme:

• inverse
• professional (core brand only)
• professional-inverse (core brand only)
• ft-live (core brand only)

a {
	@include oTypographyLink($theme: 'professional');
}

To create a custom link style set the $theme argument to a map:

• base: an o-colors palette colour name or colour for the link
• hover: an o-colors palette colour name or colour for link on hover
• context (optional): an o-colors palette colour name or colour to indicate the background colour behind the link (defaults to paper for the core brand, white otherwise)

.my-custom-link {
	@include oTypographyLink($theme: ('base': 'claret', 'hover': 'claret-30'));
}

oTypographyList

oTypographyList outputs styles for lists such as ul or ol elements and styles child li elements. It does not output specific font styles such as font size, weight, etc. Font styles are instead inherited from the parent element.

oTypographyList by default outputs only shared styles between all list types. To output all styles for a list type set the $type argument to either unordered or ordered.

E.g. to output styles for an unordered list:

.my-unordered-list {
	@include oTypographyList('unordered');
}

Use $include-base-styles to avoid duplicating shared styles between list types:

.my-list {
	@include oTypographyList();
}

.my-list--ordered {
	@include oTypographyList($type: 'ordered', $include-base-styles: false);
}

.my-list--unordered {
	@include oTypographyList($type: 'unordered', $include-base-styles: false);
}

oTypographyCaption

oTypographyCaption outputs styles for credit/captions, e.g. for photo or video elements.

caption {
	@include oTypographyCaption();
}

oTypographyFooter

oTypographyFooter outputs styles for footer elements.

footer {
	@include oTypographyFooter();
}

oTypographySub and oTypographySuper

oTypographySub and oTypographySuper provide styles for sans-serif subscript and superscript elements.

sup {
	@include oTypographySuper;
}

sub {
	@include oTypographySub;
}

Type Mixins

If you want to output only the font-family, font-size, and line-height, with no extra styles, use the type mixins.

• oTypographySans - Typically for UI elements.
• oTypographySerif - Typically for editorial body copy.
• oTypographyDisplay - Typically for editorial headings.

These mixins take arguments:

• scale: The number on the font scale from -2 to 10, or a map of scales to specify the scale responsively at different breakpoints. This sets a font-size and line height according to the font scale.
• line-height: The line-height value to set. Defaults to the line-height for the chosen scale or null if no scale is chosen.
• weight: The weight value to set, e.g. regular, semibold, bold. null by default.
• style: The style value to set, normal or italic. null by default.
• include-font-family: Whether to output the font-family property. true by default.
• include-progressive: Whether to output progressive font loading styles. true by default.

Output a font-family property only for the serif font.

@include oTypographySerif();

Output font-family, font-size, and line-height for the sans font.

@include oTypographySans($scale: 1);

Output font-family, font-size, and line-height for the serif font responsively. The scale is 0 by default, 1 on a medium display, 2 on an extra large display.

@include oTypographySerif($scale: ('default': 0, 'M': 1, 'XL': 2));

Output font-family, font-size, and line-height for the display font. Set a custom line-height of 1.6.

@include oTypographyDisplay($scale: 1, $line-height: 1.6);

Output font-family, font-size, line-height, font-weight, and font-style for the serif font.

@include oTypographySerif($scale: 1, $weight: 'bold', $style: 'italic');

Output sans font properties without the font-family property. This is useful if modifying the scale of existing typography where the font family is inherited and does not need repeating.

@include oTypographySans($scale: 1, $style: 'italic', $include-font-family: false);

Output serif font properties without sizes for the fallback font (without progressive font loading).

@include oTypographySerif($scale: 1, $style: 'italic', $include-progressive: false);

Line Width Capping

If you need to cap the line width, o-typography provides a function which limits that value based on the size of the font and an optimal amount of characters per line (65~). Limiting the line length of typography improves readability.

max-width: oTypographyMaxLineWidth();

Use A Custom Font

To set a custom font, first register the font using o-fonts.

Then set the custom font using oTypographySetFont before calling any other o-typography mixins. It accepts a font type (sans, serif, or display) and the custom font family.

// Set custom sans font.
@include oTypographySetFont($type: 'sans', $family: 'MySansFont, sans');
// The custom sans font is now output by other `o-typography` mixins such as `oTypography`.
@include oTypography();

Use A Custom Font Scale

o-typography supports multiple fonts scales, so each font may use a different scale. To register a custom scale use oTypographyDefineFontScale. The mixin accepts the font family the scale is for and the scale map (a map of scale numbers to font size/line height).

If defining a scale for a custom font, first set the custom font.

$example-custom-font-family: 'MySansFont, sans';
$example-custom-font-scale: (
	-2: (12, 16), // $scale: ($font-size, $line-height)
	-1: (14, 16),
	0: (16, 20),
	1: (18, 20),
	2: (20, 24),
	3: (24, 28),
	4: (28, 32),
	5: (32, 32),
	6: (40, 40),
	7: (48, 48),
	8: (56, 56),
	9: (72, 72),
	10: (84, 84),
);

@include oTypographyDefineFontScale($example-custom-font-family, $example-custom-font-scale);

Customisation

o-typography provides mixins to set a custom font and a custom font scale. If your project uses the whitelabel brand, o-typography provides the option to customise typography further with the oTypographyCustomize mixin.

Currently oTypographyCustomize can only update heading styles of whitelabel brand projects (please contact Origami to request more options). oTypographyCustomize accepts a map of configuration where each key is a heading level (one-six) heading-level-[level] to a map of heading scales and weights:

• weight: The heading weight (e.g. semibold)
• scale: The default heading scale, used when no other scales are set (e.g. 5)
• scale-s: The heading scale for small viewports and above.
• scale-m: The heading scale for medium viewports and above.
• scale-l: The heading scale for large viewports and above.
• scale-xl: The heading scale for extra-large viewports and above.

In the below example, we update the size and weight of h1 and h2 headings:

$o-brand: whitelabel;
@import '@financial-times/o-typography/main';

// 1. Set a custom font.
// See "Use A Custom Font".

// 2. Set a custom typographic scale.
// See "Use A Custom Font Scale".

// 3. Customise typography variants.
@include oTypographyCustomize((
	'heading-level-one': (
		'scale': 5, // Update the size of h1.
		'scale-s': 7, // Increase the size of h1 on small devices and above.
		'weight': 'semibold' // Update the weight of the h1.
	),
	'heading-level-two': (
		'scale': 6 // Update the size of h2 (up to h6 is supported heading-level-six).
	)
));

// 4. Output typography styles.
h1 {
	@include oTypographyHeading($level: 1);
}

h2 {
	@include oTypographyHeading($level: 2);
}

For more details is the oTypographyCustomize SassDoc.

JavaScript

o-typography uses JavaScript to progressively load fonts to prevent a flash of invisible content (FOIC) if the web-fonts are taking a long time to load.

Unless you're using the Build Service no JS will run automatically. You must either construct an o-typography object or fire the o.DOMContentLoaded event, which oTypography listens for.

Constructing o-typography

import oTypography from '@financial-times/o-typography';

const otypography = new oTypography();

Firing an oDomContentLoaded event

document.addEventListener('DOMContentLoaded', function() {
	document.dispatchEvent(new CustomEvent('o.DOMContentLoaded'));
});

Both methods will trigger the font loading scripts. This will remove the loading classes from the html enabling progressive font loading.

Troubleshooting

Fonts not loading in IE11

This is likely due to a misconfigured Vary header. In IE11 if the Vary header contains the name of a header which the browser is not aware of E.G. FT-Site, then it will cancel downloading the fonts part way through recieving the response yet still report the response as having a 200 HTTP status code. The solution to this is to remove the erroneous Vary header values or to remove the Vary header altogether. You can read more about how IE handles the Vary header on MSDN.

Fonts not loading in any browser

This is likely due to the server sending the fonts having misconfigured Cross Origin Resource Sharing (CORS). The solution to this is to set the header Access-Control-Allow-Origin with the value * for any font requests.

Migration guide

Contact

If you have any questions or comments about this component, or need help using it, please either raise an issue, visit #origami-support or email Origami Support.

Licence

This software is published by the Financial Times under the MIT licence. For more see the demos in the registry.