A simple header_tag module to let you change the theme on your Phoenix site.
This is a standalone add-on and makes no changes to core files.
Comes with 18 Bootstrap 4 themes to select from. You can make further changes to each by using the color tweak add-on.
That’s it simply copy all files of the into relevant sections and go to admin modules /header tags and install. You can then select the required theme in admin.
Has been tested on Phoenix 18.104.22.168 only. Enjoy!