Still messing around with bootstrap. Actually it has quite a big impact on all themes if it is integrated in core red matrix. So there has to be done some tweaking in the bootstrap css to prevent all themes from breaking. But some elements really improve the clarity of the ui like the panel elements I tried here on the left side. I am just asking myself if this should be done only on theme level or as new default in core, which would mean that existing themes would be changed. Those settings can still be overridden in the theme css.