Changing logo when mega menu is open

Does anyone out there know how to use CSS to change the site logo (white version to black version) ONLY when a mega menu is open/active?

Context: I have both black and white versions as separate files on my site. The black version is the primary logo throughout the site, but I have used this code to switch to the white version on the homepage until you scroll.

//// HOME PAGE INITIAL WHITE LOGO ///

/**desktop logo**/
@media screen and (min-width:767px) {
#collection-642dd8240a60c7018cf63f5d .header-title-logo img {
content: url("https://static1.squarespace.com/static/642cf2bb3411145e70873b6a/t/64401e41b9f32a191d16461e/1681923649471/Lock+and+Mortice+Logo+White-1000.png") !important;
max-height:inherit !important;

  }
}

/**mobile logo**/
@media screen and (max-width:767px) {
#collection-642dd8240a60c7018cf63f5d .header-display-mobile .header-title-logo img {
content: url("https://static1.squarespace.com/static/642cf2bb3411145e70873b6a/t/64401e41b9f32a191d16461e/1681923649471/Lock+and+Mortice+Logo+White-1000.png") !important;
max-height:inherit !important;

  }
}

/* SCROLLS TO BLACK HEADER */
header#header.shrink {
    background: #FFFFFF !important;
    transition: 0.5s ease-in;
}

header#header.shrink img {
    filter: brightness(0) invert(0);
}

header#header.shrink .header-nav-list * {
    color: #282829;
      transition: 0.2s ease-in;
}

header#header.shrink .header-actions * {
    fill: #282829;
    stroke: #282829;
}

//// end of HOME PAGE NAV edits ///

-----

This is what I tried, with no luck so far. (It does change the navigation colour successfully!)

.mega-menu-open .header-announcement-bar-wrapper, .mega-menu-open { 
.header-nav *, nav.header-menu-nav-list * {
    color: #282829;
    transition: 0.1s ease-out; } }

.mega-menu-open .header-announcement-bar-wrapper, .mega-menu-open {
.header-title-logo img {
content: url("https://static1.squarespace.com/static/642cf2bb3411145e70873b6a/t/64480560c173a917181c7029/1682441568120/Lock+and+Mortice+Logo+Black-1000.png") !important;
  max-height:inherit !important;
  z-index:999999 !important;
  } }

https://decagon-caribou-s63f.squarespace.com/

PW; blackpanther