Classic is a new core theme which combines the block navigation of the deprecated Clean theme and the customisation options of the Boost theme
The Classic theme is a child theme of Boost, using the upstream Bootstrap 4 Stable library, with a general look inspired by the Clean theme. The amount of CSS added on top of the Boost theme CSS has been kept to a minimum.
Customising the Classic theme
The theme provides a number of customisation options previously found on the Clean theme settings page.
This changes the navbar background color to the brand colour. By default, it is set to blue as shown in the previous screenshots. Links and icons will be shown in a shade of white.
Moodle presets are files containing a list of custom Bootstrap variables and raw SCSS that can be used to customise themes. The Classic theme uses the exact same preset structure as Boost, so preset files can easily by reused.
The theme allows selecting a background image to be used on all pages.
The branch colour is used as the default colour for the inverted navbar background color, links and buttons.
The Classic theme provides the same customisation options as the Boost theme for injecting raw SCSS. These settings allow users to have the same results as using Moodle presets.
Using Classic as a parent theme
The Developer documentation on Themes contains useful information for developing Classic-based themes.