Are there possibilities to have the item toolbar of k2 take the color of the used template?

Item toolbar is white, template background black.

Can't get rid of it.

Take a look with firebug. the div.itemtoolbar is being styled by k2.css - search there and change the background color there if you want the entire site styled that way. if not, read about k2 overrides and from jiliko.net onecss4k2 plugin to style things differently for different categories on the site.