Neenu,
I wouldn't try to modify the XBL component. This is delicate code and if you modify it you will have trouble upgrading Orbeon Forms to a newer version.
Instead, add your own CSS file:
https://doc.orbeon.com/form-runner/styling/css.html#writing-your-own-css https://doc.orbeon.com/configuration/properties/form-runner.html#adding-your-own-cssAnd do the styling with CSS only.
Now you should be able to create a CSS rule such as:
:not(.incomplete):not(.not-started)
or something like this without needing a new CSS class.
For Orbeon Forms 2017.2, we also plan some improvements to the wizard status:
https://github.com/orbeon/orbeon-forms/issues/3059Regards,
-Erik