Map<String, CellStyle> styles = new HashMap<String, CellStyle>();
short borderColor = IndexedColors.GREY_50_PERCENT.getIndex();
CellStyle style;
Font titleFont = wb.createFont();
titleFont.setFontHeightInPoints((short)48);
titleFont.setColor(IndexedColors.DARK_BLUE.getIndex());
style = wb.createCellStyle();
style.setAlignment(CellStyle.ALIGN_CENTER);
style.setVerticalAlignment(CellStyle.VERTICAL_CENTER);
style.setFont(titleFont);
styles.put("title", style);
Font monthFont = wb.createFont();
monthFont.setFontHeightInPoints((short)12);
monthFont.setColor(IndexedColors.WHITE.getIndex());
monthFont.setBoldweight(Font.BOLDWEIGHT_BOLD);
style = wb.createCellStyle();
style.setAlignment(CellStyle.ALIGN_CENTER);
style.setVerticalAlignment(CellStyle.VERTICAL_CENTER);
style.setFillForegroundColor(IndexedColors.DARK_BLUE.getIndex());
style.setFillPattern(CellStyle.SOLID_FOREGROUND);
style.setFont(monthFont);
styles.put("month", style);
Font dayFont = wb.createFont();
dayFont.setFontHeightInPoints((short)14);
dayFont.setBoldweight(Font.BOLDWEIGHT_BOLD);
style = wb.createCellStyle();
style.setAlignment(CellStyle.ALIGN_LEFT);
style.setVerticalAlignment(CellStyle.VERTICAL_TOP);
style.setFillForegroundColor(IndexedColors.LIGHT_CORNFLOWER_BLUE.getIndex());
style.setFillPattern(CellStyle.SOLID_FOREGROUND);