style.css: remove unneeded csslint rule.
style.css: remove unneeded csslint rule.

FeodorFitsner/mpc-hc.org,kasper93/mpc-hc.org,Underground78/mpc-hc.org,mpc-hc/mpc-hc.org,FeodorFitsner/mpc-hc.org,kasper93/mpc-hc.org,Underground78/mpc-hc.org,Underground78/mpc-hc.org,FeodorFitsner/mpc-hc.org,mpc-hc/mpc-hc.org,mpc-hc/mpc-hc.org