If you just want a standard green “Accept” button that closes the header and nothing more, use this shortcode. It is already styled, you don’t need to customise it.
Alternatively you can add a colour value. Choose from: red, blue, orange, yellow, green or pink.
Careful to use the British spelling of “colour” for the attribute.
This is the “main button” you can customise.
This is the cookie settings button rendering shortcode.
This is the cookie reject button shortcode.
This is the “read more” link you can customise.