Hi, to be honest the only way now is... to customize SPPB code.

OR

Find extra SEO/SEF extension that allows adding extra fields for Pages built using SPPB.

thanx Paul.

How to custom extra css code for SPPB.

Each Page has a option to add custom CSS for whole page. It's icon below Open Graph fields.

i know this field. but i don't know custom css code

meta name="twitter:card" content="summary_large_image"

i tried to add this code but nothing has changed.

Thanx

But this is not CSS, common....!!!! Have you ever read any book about HTML ?

All meta tags are HTML code

HTML =/=CSS

As I said before using default SPPB options you cannot add that tag inside < head > area.