I think you want to add this to your kindo css file , because kindo script will overwrite your css:
kindo.common.min.css:line # 9
.k-grid td
this is the css for the td just add your background color.
Edit:
Maybe this is what you are searching for:
$(document).ready(function(){$(".k-grid td:contains('Jan')").css("background-color","#000099");});
this is how it looks