In Moodle 3.2 we introduced theme Boost (based on Bootstrap 4alpha) with the aim of continually progressing the look and feel of Moodle and providing increased consistency across the different platforms (web, desktop, mobile).
In Moodle 3.5 we upgraded Boost to Bootstrap 4 stable allowing us to take advantage of the improvements in the Bootstrap framework.
Currently, we still support the Clean and More theme, which are both based on Bootstrap version 2. Supporting multiple frameworks and themes increases our development and testing efforts as all new features require development and testing across the different themes. In turn this means that less time is available to work on new features, bugs, and other user-facing functionality.
In the long term this is not sustainable and also not beneficial. We would rather focus our efforts on improving the core theme and ultimately serving our users better. Hence, we have established the following plan to phase out support for themes based on Bootstrap 2.
For Moodle 3.6:
Move Clean, More and bootstrapbase to the plugin repository; we will leave sufficient support in Moodle 3.6 core to enable users to download and use Clean and More should they require this (e.g. if they have custom themes based on Clean).
Provide a ‘Classic’ theme, based on Bootstrap 4 that is more in-line with the Clean theme, retaining the 2 and 3 column grid layout, and the classic navigation block.
This provides a solution for those users who prefer the classic style navigation and sufficient time for custom themes to be redeveloped based on Bootstrap 4.
For Moodle 3.7:
Remove the support for Clean and More from the Moodle core distribution.
Going forward all themes to be based on Bootstrap 4 based on the ‘Classic’ theme or Boost.
Open Source Development Coordinator