Style background color and line style of panel Accordion

Hi there,

I want to style the background color (set to white) and the lines (no lines/box) of the accordion header.

However, I am not sure how to do it.
I tried:

 pn.Accordion(('Equation Details', eq_), width=width_, styles={'header_background': 'white', 'background': 'white', 'line_width': '0px', })

However, the header still looks likes the normal one:

Which parameters do I need to set?

Thank you in advance!