You can choose to use an external or internal cascading style sheet (CSS).
Open the BCC Home page > Service Administration > Service Administration Configuration >
Project Name> Self Service >Site Name> Home Page > Styles.If you select External, you can specify a URL for your CSS.
If you select Internal, the default CSS is displayed in a text editor where you can modify it if desired.
Note: All site pages let you specify internal or external CSS. If CSS is not defined for a page, it will use the home page CSS by default.
