overview: fix accessibility of the headers
overview: fix accessibility of the headers

Fixes #15187

cockpit-project/cockpit,mvollmer/cockpit,garrett/cockpit,mvollmer/cockpit,mvollmer/cockpit,cockpit-project/cockpit,cockpit-project/cockpit,cockpit-project/cockpit,garrett/cockpit,martinpitt/cockpit,garrett/cockpit,martinpitt/cockpit,martinpitt/cockpit,martinpitt/cockpit,cockpit-project/cockpit,garrett/cockpit,garrett/cockpit,mvollmer/cockpit,martinpitt/cockpit,mvollmer/cockpit