Can't get rid of w-nav background

Hi All,

I published a while ago and I’m making regular updates.
Since today, 2020/12/08, the Nav Bar has a .w-nav class with a background #ddd that only shows once published.

I did not set any class “w-nav”, and the w-nav{background: #ddd;} doest not shows in the Designer. It will only shows on the live site: .

I tried adding a custom CSS script in the header :


	.w-nav {
    background: none !important;

It does not work.

Thanks in advance for your help!

Here is my site Read-Only: