In the Ukrainian wiki, some styles override TemplateStyles on the Main Page. These are:

.skin-theme-clientpref-night .page-Main_Page .mw-parser-output :not(.notheme):not(a) {
    background: inherit !important;
    color: inherit !important;
    border-color: var(--border-color-subtle, #c8ccd1) !important;
  }

The problem with them is that drop-down menus are displayed transparently like this:

As of now, I have made changes to TemplateStyles that the Main Page is using, and the Main Page should work in dark mode without this override.

The same photo without overriding: