This is something I have had difficulty understanding, because at the moment Barceloneta is the default theme for Plone - however the whole styling stack makes use of but overrides a bunch of default Bootstrap styling elements. It's like a Frankenstein version of the aforementioned framework. Using Diazo is great, but implementing the front-end theme with the back-end control panel is a nightmare and has you digging around in rules and conditions where it should be much simpler to do. If I want to to separate the the back-end styling with the front-end stuff, things break.
Then to top the cherry on the pie is the implementation of various rows, containers and columns in templates which when rendered all together using macros, rules and TAL just ends up in a mosh-pit of confused Bootstrap elements in no logical hierarchy...
There are a few themes that were created for Plone at GSoC and they all inherit the same problems and broken responsiveness as a result of this.
Much better in my opinion would be to use a default Bootstrap layout and styling with some CMS independent styling which can be easily removed and overridden and then keep only the toolbar and configuration panel the same, much like in Drupal from what I've seen.
What are other peoples opinions on this and what is everyones workflow for totally customizing a Plone visual experience for a web application. How would you implement the back-end into the front-end theming of Diazo. I had real problems with this, does someone have some examples..?