40/replication_package/oTree/_static/global/matrix.css

.rotate90 {
    -webkit-transform: rotate(-90deg);
    -moz-transform: rotate(-90deg);
    -ms-transform: rotate(-90deg);
    -o-transform: rotate(-90deg);
    transform: rotate(-90deg);
    float: left;
    margin-top: 1em; // TODO: do not hardcode to center align
}