Conditional Formating

Hi guys

I m trying to format my row colors conditional on my row index being superior to a number
I ve tried

style_data_conditional=[{
‘if’ : {‘filter’: ‘row_index > num(7)’ },
‘color’:‘blue’
}]

and

style_data_conditional=[{
‘if’ : {‘row_index’: ’ > num(7)’ },
‘color’:‘blue’
}]

none of which seems to work

any idea how I can do this?

Thanks