To apply styles to subtotal levels:
1. Add Subtotals to the List.
2. Select a cell in the List area, and press Ctrl+Shift+* (in Excel 2003, press this or Ctrl+A) to select the List.
3. From the Data menu, select Group and Outline, and then Settings.
4. Click Apply Styles. The automatic style is applied to Subtotal lines level 2.
To modify the automatic style:
1. From the Format menu, select Style.
2. From Style name in the Style dialog box, select RowLevel2 (the style RowLevel2 & RowLevel1 are automatically created upon clicking Apply Styles, as described above).
3. Click Modify, and select any desired format.
Screenshot // Applying Styles to Subtotal Rows