Marianne80

If you want to style the icon differently on this CategoryPage you would go the CSS styling route as outlined by Tariq.

If you are going after an individual icon, e.g. for the "Enterprise" category in your screenshot from https://community.visma.com/t5/Visma-Unique/ct-p/NO_UN

you would include the individual icon's node class as well, e.g.

.CategoryPage .lia-node-no-un-enterprise .board-icon .lia-fa-icon:before {
    color: red;
}

Keep in mind that you need to add styling for every other page you would like to see this icon styled differently.

NB: Some widgets might not expose the icon class needed to differentiate a specific category's icon from the others.

The most likely explanation is that the "Sweden" category has some permission restrictions which hide it. The search's "Location" filter is created based on the current user's (or the default user's if there's no member signed in) permission set. I can access https://community.visma.com/t5/Sverige/ct-p/community_sw though which I think is the category you are missing.

Another option could be that you checked the "Hide from lists and menus" property for the "Sweden" node on the community structure admin screen. You might want to check that as well.