Are you talking about that .mx-grid
class thing?
Style specific row:
.mx-datagrid tr:nth-child(4){
background: #ff0000!important;
}
Style specific cell
.mx-datagrid tr:nth-child(2) > td:nth-child(3) {
background: #00ff00!important;
}
Style specific col
.mx-datagrid td:nth-child(3) {
background: #0000ff!important;
}