Background color not

I have been using your TablePress plugin for some time and found it a great plugin for adding tables to pages. I am now trying to add special CSS formatting to a specific table to change the background color. I read your FAQ about adding CSS styling to the Plugin options page and updated accordingly. I am trying to set the background color and am using the following:

.tablepress-id-17 {
width: 50%;
margin: 0 auto 1em;
font-weight: bold;
background-color: #9ef3a5 !important;
}

.tablepress-id-17 thead th,
.tablepress-id-17 tbody td {
border: 2px solid #000000 !important;
}

Unfortunately, the background does NOT get set. Please advise.

The page I need help with: [log in to see the link]