@bbc/gel-foundations

gel-foundations -

This package provides a range of string constants for use in CSS, intended to help implement BBC GEL-compliant webpages and components.

Exports

/breakpoints - GEL breakpoints, as well as typography breakpoints. These use the GEL grid sizes which can be found in the GEL Grid guidelines. /spacings - GEL spacings and GEL Grid margins and gutters. These use the GEL grid spacing sizes which can be found in the GEL Grid guidelines. /typography - GEL type sizes and font stacks. These are based on the GEL Typography definitions which can be found in the GEL guidelines. More details on how the type sizes were implemented for this package are available here.

Installation

npm install @bbc/gel-foundations --save

Usage

import { GEL_GROUP_3_SCREEN_WIDTH_MIN } from '@bbc/gel-foundations/breakpoints';

import { GEL_GUTTER_ABOVE_600PX } from '@bbc/gel-foundations/spacings';

import { getLongPrimer } from '@bbc/gel-foundations/typography';

These values can then be used directly within CSS declarations in code:

import { css } from 'styled-components';

const SomeStyledComponent = css`
  font-family: ${GEL_FF_REITH_SANS};
  ${getLongPrimer(script)};

  @media (min-width: ${GEL_GROUP_3_SCREEN_WIDTH_MIN}) {
    grid-gap: ${GEL_GUTTER_ABOVE_600PX};
  }
`;

To allow the typography to be fully accessible and responsive, please note that you should apply a default font-size to the document root (e.g. html { font-size: 100% }).

Our typography uses rem for font-size and line-height. The rem unit represents a size relative to the document root, so we use that for font-size, line-height and spacing for a consistent look-and-feel across the document. You can read our detailed analysis of "REMs vs EMs for spacing" for more information.

Script support

The utility typography function (e.g. getLongPrimer('arabic')) receives a script argument which is an object with the different script GEL Types Sizes and returns the font-sizes and line-heights for the specific GEL Type (e.g. Long Premier).

You can import the script doing import { arabic } from '@bbc/gel-foundations/scripts. By default you should import the latin script as found on the GEL typography guidelines.

In addition to Latin script defaults, Psammead supports typography for a number of other scripts. We have grouped the scripts that share similiar features as follows:

Group Name	Services	Rationale
latin-and-cyrillic	News, Hausa, Gahuza, Somali, Swahili, Igbo, Pidgin, Afaan Oromo, Yoruba, Azeri, Indonesia, Uzbek, Serbian, Russian, Ukrainian, Kyrgyz, Uzbek	The typography values for Latin and Cyrillic characters are identical
latin-with-diacritics	Vietnamese, Mundo, Afrique, Brasil, Turkish	The diacritics make these values differ from Latin
arabic	Arabic, Pashto, Persian, Urdu	Group as they use the Arabic alphabet
no-ascenders-or-descenders	Korean, Japanese, Zhongwen, Ukchina, Tigrinya, Amharic	Group all alphabets without ascenders or descenders. This could be implemented as chinese, korean, ethiopic
devanagari-and-gurmukhi	Hindi, Nepali, Gujarati, Punjabi, Marathi, Telugu	The typography values for Devanagari and Gurmukhi characters are identical
thai	Thai	Bespoke to the Thai characters
bengali	Bengali	Bespoke to the Bengal characters
burmese	Burmese	Bespoke to the Burmese characters
sinhalese	Sinhala	Bespoke to the Sinhalese characters
tamil	Tamil	Bespoke to the Tamil characters

Contributing

When adding a new export to this utility package the export tests also need to be updated. When removing an exisiting export from this utility package the export tests need to be updated and the package version requires a major change (EG: 1.2.1 -> 2.0.0) as this would be considered a breaking change as functionality is being removed.

Psammead is completely open source. We are grateful for any contributions, whether they be new components, bug fixes or general improvements. Please see our primary contributing guide which can be found at the root of the Psammead respository.

Code of Conduct

We welcome feedback and help on this work. By participating in this project, you agree to abide by the code of conduct. Please take a moment to read it.

License

Psammead is Apache 2.0 licensed.