Problems changing row colour

I’ve imported an excel file into Tablepress and I’m now trying to amend row colours via the Custom CSS option in the Plugin options tab but I’m having big problems doing so. The row that I’ve changed the colour coding for is:

.tablepress-id-2 .row-3 td {
background-color: #OOFF99;
}

But when I save and check the table the colour hasn’t changed. In fact I’m not absolutely certain that the CSS corresponds with the correct table as the number of rows do not match in either. Additionally there is a big gap in the row numbers for the CSS, i.e. coding jumps from row 6 to row 43 with nothing in between.

Any ideas would be greatly appreciated.

Thank you