Breakpoint entities were introduced to core in #1734642: Move breakpoint module into core.
Breakpoints are only available to module developers through code. The intent of introducing breakpoints to core was to also provide a UI for establishing breakpoints for modules and themes to leverage.
Breakpoints are best established at the point where content no longer fits well within the available screen real estate. Site builders should be able to establish breakpoints through a view of their content, in the context of a theme.
- Discuss approach
- Discuss design
- Clean up code
User interface changes
Introduction of a theme preview within the context of configured breakpoints.