Sticky % transparent menu background

Hello good day.
I’m trying to make the background of the menu and the submenu transparent.
I found this CSS code on your support page:

#header-inner:not(.stuck) #header-inner-bg {
background: rgba(39, 26, 26, 0.17) !important;
}

But I can not make the submenu transparent.
attached image screenshot of the home.
Could you help me?
Thank you very much.

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