How can I adjust the size of search bar in the header menu ?

[getnet bantie]

I am creating new portal for an app and I want to add a search bar to the header menu by adjusting its size to be small.

[suvro]

Check this out

https://community.servicenow.com/community?id=community_question&sys_id=74e032f11b595c507a5933f2cd4bcb79