Hello Abhijit, 

Thanks for posting your query in PSC :)

From the attached screenshot, I see this setting from skin rule is of Container with Default format.

Underline is appearing because of Border botton mixin attribute added in Expanded Border style under Header tab. To remove it, try below solution:

- Select Specify styles

- Check/Enable 'Apply to all sides'

- Choose the value of None for All borders

Refer the attached screenshot for your quick reference.

PS: My observation is from Pega 7.4.

I am investigating on the header position of Fieldset Default title and will keep you posted. 

Regards,

Rincy

Hello Abhijith, 

Find below finding regarding alignment of the header for Fieldset Default section:

The header title is coming from the header type set as Fieldset in  pzSelectivePreviewHeaderOtherTemplaterule. View container settings's header type in the properties of last section include. Changing the header type from Fieldset to Bar with header type as heading 2 resolves the behavior. However, note that this is final rule.

I hope this helps. 

Regards,

Rincy