code{counter-reset:step;counter-increment:step calc(var(--start, 1) - 1)}code .line:before{content:counter(step);counter-increment:step;width:1.5rem;padding-right:.5rem;margin-right:.5rem;display:inline-block;font-weight:700;text-align:right;color:#616a75;border-right:2px solid currentColor}