PowerBI each visual has outside border or header that cannot be disabled

Hello Community, 

I am using an existing model and all the visual in that PBIX by default has the outside grey header box. I can't figure out how to disable it. Due to the grey border, I can't move my visual all the way to the top as Power BI consider the top grey border box is the boundary of my visual?

I check the format for each visual, there is no such board or header enable; Also checked the theme, looks normal.

Any thoughts and ideas? Much appreciated