ConfirmDialog on Vaadin flow doesn't change width?

ConfirmDialog cd = new ConfirmDialog();
cd.setConfirmText("Confirm");
cd.setCancelable(true);
cd.setCancelText("Cancel");
cd.setHeader("Header");
cd.setText("Text text text text text");
cd.setWidth("1200px");
cd.open();

width is not changed.
how can I change the width?