Applies a style to the cell. When a style is applied - rather than set (see Cell.Style ) - only the differences between the new style and style properties previously assigned to the cell (through the ExcelWriter API) will take effect. For example, if the cell has a background color and the new style applied does not contain a background color, the cell's color will not be affected. However, if the new style includes a background color, it will replace the existing background color of the cell.
