dashboard top menu => rtl

[Mark Lin]

Hello,
Trying to rtl the top menu,
add this line to jquery.ui.menubar.css,
but nothing happan
where i'm wrong?

*original :*

.ui-menubar-item {
float: left;
}

*new/after :*

.ui-menubar-item {
float: left;
}
.ui-menubar-item-rtl {
float: right;
}

Thank you