PdfContentByte cb = writer.getDirectContent();
// headers
Phrase fullTitle = new Phrase("Full Title", font24B);
float currentY = document.top();
ColumnText ct = new ColumnText(cb);
ct.setSimpleColumn(fullTitle, document.left(), 0, document.right(), document.top(), 24, Element.ALIGN_JUSTIFIED);
ct.go();
currentY = ct.getYLine();
currentY -= 4;
cb.setLineWidth(1);
cb.moveTo(document.left(), currentY);