.icon-read { background-image: url(../images/bullet-black-icon.png); }
.icon-unread { background-image: url(../images/bullet-green-icon.png); }

table td.subject { padding-left: 16px; }

table tr.unread td.subject {
    font-weight: bold;
    background: transparent url(../images/bullet-green-icon.png) no-repeat center left;
}

table tr.read td.subject {
    background: transparent url(../images/bullet-black-icon.png) no-repeat center left;
}