Hi there,
the Table Block is really limited on what you can do with individual cells.
If you wanted to target just that specific 2 row table then you can:
1. Add this CSS to your site:
.bi-color-table tr:first-child td:first-child {
background-color: #f00;
}
.bi-color-table tr:nth-child(2) td:first-child {
background-color: #0f0;
}
Change the background colors to suite.
2. Select the Table Block and in Advanced > Additional Class(es) field add: bi-color-table