This file describes API changes in /theme/boost
information provided here is intended especially for theme designers.

=== 3.7 ===

* Templates and renderers moved to core.

* Behat override steps moved to core.

Form element template
---------------------
A 'wrapperid' has been added to 'templates/core_form/element-template.mustache' to restore unique ids
on Boost form element wrappers. This restores the same unique element ids seen on elements in BS2
themes, which were mistakenly dropped when introducing the Boost theme.

=== 3.5 ===

The Boost theme now uses Bootstrap 4 Stable (BS4S).

We are trying to use as much BS4S classes in MDL Templates to reduce the amount of Moodle CSS.

The biggest changes are:

JavaScript
----------
* All Bootstrap javascript has been updated.

Sass
----
* A number of variables are no longer available in Bootstrap 4 Stable. For now a bs4alpha compatibility file has been added, see scss/bs4alphacompat.scss which translates veriable names from the Alpha version to the stable version.

* m-t-* and other spacing utilities should be replaced with mt-*.

The units that were used for margins have changed too
m-t-1 is now mt-3
m-t-2 is now mt-4
m-t-3 is now mt-5


Grid and Flexbox
----------------
The Boostrap grid uses CSS's flexbox grid to build layouts.

New breakpoints for grids have been added:
.col-*  <576px
.col-sm-* >= 576px
.col-md-* >= 768px
.col-lg-* >= 992px
.col-xl-* >= 1200px

All usage of '*-xs-*' have been dropped. So what used to be col-xs-6 should now be written as col-6.

*-md-* has become *-lg-*, and *-lg-* has become *-xl-*.

Typography
----------
Boostrap 4 uses a native font stack that selects the best font-family for each OS and device. For font sizing the browser default root font-size (typically 16px) is used. this variable can be changed using the variable '$font-size-base'.
In the default Boost preset we use: "0.9375rem" which computes to 15px on most browser.

Presets
-------
The structure of preset files have changed. The new structure of a preset file is:

// Space to set variables.
$font-size-base: 0.9375rem

// Import FontAwesome.
@import "fontawesome";

// Import All of Bootstrap.
@import "bootstrap";

// Import Core moodle CSS.
@import "moodle";

// Space to use Bootstrap mixins and extends.
.navbar {
  @include shadow();
}

Bootswatches
------------
Bootstrap 4 bootswatches can be imported using the theme/boost/cli/import-bootswatch.php script. Generated bootswatches can be added in the theme boost settings page.

Changed Components
------------------
Cards need this structure
 class='card'
    class='card-body'
This used to be 'card-block'

The header.mustache template has been replace by a navbar.mustache template for name consistancy with Bootstrap

A new header.mustache template has been created served from core/core_renderer.php. This should be move to core at some point.


=== 3.4 ===
* For improved accessibility, the footer links for boost have been changed to use $bg-inverse-link-color (defaults to white) and
  now have an underline text-decoration. To override the link colour simply set $bg-inverse-link-color in your preset file or
  theme scss.
* To match the new primary colour we are switching to using the UX pallette, which uses a purple colour for info. To override,
  set $brand-info in your preset file or theme scss.