Blog menu black but the entire website menu is white

Site URL: https://www.gengepartners.com/blogue/blog-post-title-one-s2xwf

Hello, my website menu is white, but the menu on the blog stays black... 

When I change the menu, it changes to white, but it turns back to black as soon as I save it. 

Could you please help me? 

Thank you! 

Try adding to Design > Custom CSS

/* Individual posts header color */
body[class*="collection-type-blog"].view-item header#header a {
    color: white;
}

It works ! thank thank you very much ! 

Have a great day.