style.css: switch to border-box for navbar's vertical divider
style.css: switch to border-box for navbar's vertical divider

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