zoneminder/web/skins/classic/css/base/views/log.css

tr.log-fat td {
    background-color:#ffcccc;
    font-weight: bold;
}

tr.log-err td {
    background-color:#ffcccc;
}

tr.log-war td {
    background-color: #ffe4b5;
}

tr.log-dbg td {
    color: #666666;
    font-style: italic;
}