It looks like you're new here. If you want to get involved, click one of these buttons!
So I discovered that in your custom_superhero css in panel headers you have color from un-themed Bootstrap.
EDIT: My pc is a bit slow so my GitHub client is lagging so I cannot create pull request, but enable superhero theme and look at discussions headings. It it #F5F5F5 color and it should be #485563