Change button style only on "coverpage" version 7.1

Hi everyone!

I'm using SquareSpace 7.1.
For my coverpage I used this code to remove the header:

<style type="text/css">
    header, footer { display: none; !important; }
    section { padding-top: 0  !important; }
</style>

Now, I would like to change the button style from outline to solid.

By changing the button in the general design setting, the removed header will appear again.
Does anyone know how to change only this specific button style to solid (without showing the header again.)?

Thanks!

I see you solved. Do you still need help on this?

I still need help...

You can change button style in setting, then we will check header.

Hi tuanphan, I know. The second picture shows the changed button style and what happens.
Unfortunately, the header is visible after changing the button style for all buttons. I think because there's also a button in the header...

Any idea what to do?