Changing colors

I’m trying to change the color of the month view header (where the days are listed) and the color of the cells, but all the CSS I’m trying isn’t doing a thing. Can you please advise?

Below is what I’ve tried:

table.tribe-events-calendar thead, table.tribe-events-calendar thead tr{
background-color:#0a82cb!important;
}
table.tribe-events-calendar td {
background-color:#ffffff!important;
}