span.eqnnumber:before {
    content: "(";
}
span.eqnnumber:after {
    content: ")";
}
tr.eqnnumber {
    vertical-align: middle;
}
table.displaymaths {
    width: 100%;
}
table.displaymaths > tr {
    vertical-align: top;
}
table.displaymaths td.label {
    width: 2em; 
    vertical-align: middle;
}
table.displaymaths td.label table {
    width: 100%;
    text-align:right;
}