input an issue to github for that, but it seems that this was wrong:
So my Use-Case was i copied an changed an existing theme (Blank, its great withe the Builder, but not realy responsiv), so in that workflow i create a version of myTheme upload it, create Content with the PageBuilder, tested it and some mistakes are in the HTML, so i improved myTheme, uploaded it an then the Problems came up
no Updating own Themes is possible without loosing of existing content.
Create a Button, update Theme which creates a new Mix of Theme+Content.
Mayb be the Content must be stored, seperatly, like an xml-File. and the theme will be rendered with this content, like all php mvc-frameworks handel it, with php or twig.
use bootstrap3/4 as default, so layout elements are then
container - to be defined
rows - like section in combination with column
columns - like section in combination with row
elements - slots elements like text, image etc
Layout Elements: Container, Rows, Columns with styling of position, floating, margin, padding, background color + image
Content Elements: Text, Image, etc. with styling position, floating, margin, padding, background color + image, element specific properties
So dropping table an change it to div for more responsivness. the structure is similar useds in clickfunnels.