formstrap now supports Drag and Drop into the grid at any level (not just at the Column Field Container level).
Drag your preferred input type from the floating panel anywhere into the grid and the appropriate descendants will be created before the field is added.
This new functionality allows you to create a complex, responsive layout just by dragging and dropping fields.
Check out this video: It shows a Single Line Text field being inserted into a new Section Column in the Section Container. The required descendants (i.e. Section Column, Row and Column) are all created before the field is added.