Question: How to style expanded rows?

Hi, i'm new to React and Datatables and have trouble styling expandable rows (the text in expandable row is brekaing with every word and has no left padding: http://prntscr.com/olv159). I styled everything else in table with the help of CSS classes, but expandable rows are not assigned any CSS class.

I tried with vairations of following CSS but its not working:
td.Mui-expanded {
background-color: red !important;
padding-left: 2rem;
}
Thanks for any suggestions and help :)