prometheus/web/ui/static/css/alerts.css

.alert_header {
  cursor: pointer;
}

.alert_details {
  display: none;
}

.filters button.show-annotations {
    background-color: white;
    border-color: #adadad;
    border-radius: 0;
    color: #333;
    font-size: 0.8em;
}

.filters button.show-annotations.is-checked {
    color: #fff;
    background-color: #286090;
    border-color: #204d74;
}