we checked and can´t directly add a style for read only cells as a cell´s readonly property can be set from several source (cell, row, table or inherited).
It’s probably a lot easier to create a single shared style and assign it to the readonly cells using the ReadOnly property to detect the read only cells. T
The shared style can use theme colors.
Hope that helps.
can you please describe in more detail what you are trying to achieve ?
Did you try setting the cell style ? Or are you thinking about giving read only cells a different appearance and define it in the theme ?