.spine{--spine-node:.6rem;--spine-col:1.5rem;position:relative}.spine__rail{top:.6rem;bottom:0;left:calc(var(--spine-col) / 2);background:var(--rule);width:1px;position:absolute}.spine__line{background:var(--signal);transform-origin:top;position:absolute;inset:0;transform:scaleY(1)}@supports (animation-timeline:scroll()){.spine__line{animation:linear both spine-draw;animation-timeline:scroll();transform:scaleY(0)}@keyframes spine-draw{to{transform:scaleY(1)}}}@media (prefers-reduced-motion:reduce){.spine__line{animation:none;transform:scaleY(1)}}@media (min-width:60rem){.spine[data-cover-origin] .spine__rail{left:var(--spine-x,calc(var(--spine-col) / 2))}.spine[data-cover-origin] .spine__stages{padding-left:calc(var(--spine-x,calc(var(--spine-col) / 2)) - var(--spine-col) / 2)}}.spine__stages{gap:var(--space-6);margin:0;padding:0;list-style:none;display:grid}.spine__stage{grid-template-columns:var(--spine-col) minmax(0, 1fr);column-gap:var(--space-4);align-items:start;display:grid}.spine__node{width:var(--spine-node);height:var(--spine-node);margin-top:calc(.6rem - var(--spine-node) / 2);background:var(--signal);box-shadow:0 0 0 4px var(--paper);transition:background var(--dur-micro) var(--ease);border-radius:50%;margin-inline:auto}.spine[data-enhanced] .spine__node{background:var(--rule)}.spine[data-enhanced] .spine__stage[data-filled] .spine__node{background:var(--signal)}.spine__index{font-family:var(--font-mono);font-variant-numeric:tabular-nums;font-size:var(--step--2);letter-spacing:.08em;color:var(--ink-muted);display:block}.spine__label{font-size:var(--step-1);letter-spacing:-.01em;color:var(--ink);margin-top:var(--space-1);line-height:1.25}.spine__note{font-size:var(--step-0);color:var(--ink-muted);max-width:var(--measure);margin-top:var(--space-2);line-height:1.65}