body {
    background-image: url('skins/elastic/images/mail.jpg');
    background-size: cover;
    background-attachment: fixed;
    background-position: center;
}

/* Make content areas have some transparency */
#mainscreen, #messagelist, #messagecontframe, .uibox, .records-table, .contentbox {
    background-color: rgba(255, 255, 255, 0.9) !important;
}