How to rotate text in a column of a crosstab

Hi everyone,

I need to rotate the text in the first column of a standard Design Studio crosstab 90 degrees counter-clockwise. The class name where the properties of the first column can be defined is .sapzencrosstab-HeaderCellFirstInRow, and I tried to apply transform: rotate(-90deg), but it rotates the entire cells in the column, not just the text inside the cells, and it looks really messy.

You can see a sketch of what I am trying to achieve in the sketch below made in Excel. The values "A", "B", "C" in column "Group" should be rotated.

Thanks!