Bootstrap grid divs have been added to templates/layouts/<layoutname>/layout_view.tpl. The columns on the right and left side of the page that have been traditionally the left and right side columns are now positioned by Bootstrap, and will move below the center column in smaller device views. There are several "layoutnames", with each providing a different layout. These will be documented and added to later.
All layout is handled by Bootstrap; Tiki's former method (lite.css) is no longer used.
Prior to Tiki 13, the Theme Control feature allowed assigning of different themes to specific Tiki objects. This ability needs to be described for Tiki 13.
Also, things like column widths could be changed via the theme stylesheet, but now the Bootstrap grid is hard-coded in the layout_view.tpl file, so a method is needed for changing the layout_view.tpl being used from the front end (that is, other than by using Look and Feel admin). Documentation is needed here.
Bootstrap div classes are being added to Tiki's .tpl files to provide Bootstrap layout and styling to the page features, for example, for buttons, tabs, and tables.
The module zones are Bootstrap row divs, so modules need to be able to be assigned column width classes. (Actually only the horizontal module zones should be class="row".) A module with a Bootstrap grid class will behave as other layout columns, being the specified width and behaving responsively.