Adding stylesheet to Checkout/MyAccount Bundle of Site Builder Site

We can add external stylesheet to checkout and my account bundle of the site builder.For that first we need to add the stylesheet to the File cabinet.

To add a style sheet with a File cabinet:

1. Click the Documents tab.
2. Open the Web Site Hosting Files folder.
3. Open the Live Hosting Files folder, or open the Staging Hosting Files to test your style sheet before publishing.
4. Open the site folder.
5. Click Add File, and choose your style sheet.
   

To add stylesheet to checkout or my account bundle:
1.Commerce>sitebuilder>Tab
2.Edit Checkout/my account
3.In the tag substituition subtab,select a tag(A tag should be created prior to this).In the substitution field add the link of the stylesheet.
4.Save.