Get Excel (xlsx) from the XML data with Styles

Hi there, 

I have an XML file with many Styles, Comments, etc. It works fine if I export it as xls format using javascript. But I want it in xlsx format.

 

For that I tried to use EPPlus library to Export excel.

 

As I have mentioned that the file has styles and comments ad all, I need a way to define and use it. But I can't find the way to define all styles and assign it to the specific cell.

 

Please help.