lib: Remove duplicate css rule
lib: Remove duplicate css rule

This exact same rule is defined a few lines below once again.

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