Be able to change elements colors

Problem/Motivation

Currently the colors of the elements are always blue by default.

Proposed resolution

Be able to change the colors, put color palette in the widget options and allow select and apply bootstrap buttons 4 toohttps://getbootstrap.com/docs/4.0/components/buttons/

Remaining tasks

Create a patch.

User interface changes

Add color palette in the widget options.

API changes

None.

Data model changes

None.

Release notes snippet

None.