:root {
  color-scheme: light dark;
  --paper: #f6f1e7;
  --paper-2: #efe8da;
  --card: #fbf8f1;
  --ink: #1d1a16;
  --ink-2: #4a443b;
  --muted: #6f675b;
  --rule: #d9d0c0;
  --accent: #b8321f;
  --accent-ink: #ffffff;
  --shadow: 0 1px 0 rgba(0, 0, 0, 0.04), 0 8px 24px -16px rgba(60, 40, 10, 0.35);
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --paper: #171512;
    --paper-2: #1f1c18;
    --card: #1c1915;
    --ink: #ece5d8;
    --ink-2: #c9c0b1;
    --muted: #9c937f;
    --rule: #332e27;
    --accent: #e2593f;
    --accent-ink: #171512;
    --shadow: 0 1px 0 rgba(255, 255, 255, 0.03), 0 8px 24px -16px rgba(0, 0, 0, 0.8);
  }
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { text-decoration-thickness: 2px; }

code, pre, kbd {
  font-family: var(--mono);
  font-size: 0.92em;
}

code {
  background: var(--paper-2);
  border-radius: 4px;
  padding: 0.08em 0.35em;
}

pre {
  margin: 0;
  padding: 1rem 1.15rem;
  background: var(--paper-2);
  border: 1px solid var(--rule);
  border-radius: 8px;
  overflow-x: auto;
  line-height: 1.5;
  font-size: 0.86rem;
  tab-size: 2;
}

pre code { background: none; padding: 0; font-size: inherit; }

.wrap {
  width: min(100% - 2.5rem, 68rem);
  margin-inline: auto;
}

/* Header */

.top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1.1rem 0;
  border-bottom: 1px solid var(--rule);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  color: var(--ink);
  text-decoration: none;
  font-weight: 650;
  letter-spacing: -0.01em;
}

.brand svg { width: 26px; height: 26px; }

.top nav { display: flex; gap: 1.4rem; flex-wrap: wrap; }
.top nav a { color: var(--ink-2); text-decoration: none; font-size: 0.95rem; }
.top nav a:hover { color: var(--accent); }

/* Development notice */

.notice {
  margin-top: 1.25rem;
  padding: 0.7rem 1rem;
  border: 1px solid var(--accent);
  border-left-width: 4px;
  border-radius: 6px;
  background: var(--paper-2);
  color: var(--ink-2);
  font-size: 0.95rem;
}
.notice strong { color: var(--accent); }

/* Hero */

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.15fr);
  gap: 3rem;
  align-items: center;
  padding: 4.5rem 0 3.5rem;
}

.hero h1 {
  font-size: clamp(2.3rem, 4.5vw, 3.4rem);
  line-height: 1.05;
  letter-spacing: -0.03em;
  margin: 0 0 1.1rem;
  font-weight: 700;
}

.hero .lede {
  font-size: 1.2rem;
  color: var(--ink-2);
  margin: 0 0 1.8rem;
  max-width: 34ch;
}

.eyebrow {
  display: inline-block;
  font-family: var(--mono);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 1rem;
}

.actions { display: flex; gap: 0.8rem; flex-wrap: wrap; }

.btn {
  display: inline-block;
  padding: 0.65rem 1.1rem;
  border-radius: 6px;
  text-decoration: none;
  font-weight: 600;
  font-size: 0.95rem;
  border: 1px solid var(--rule);
  color: var(--ink);
  background: var(--card);
}

.btn.primary { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.btn:hover { filter: brightness(0.97); text-decoration: none; }

/* The packing slip document */

.slip {
  position: relative;
  background: var(--card);
  border: 1px solid var(--rule);
  border-radius: 10px;
  box-shadow: var(--shadow);
  overflow: hidden;
}

.slip-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.6rem 1rem;
  border-bottom: 1px dashed var(--rule);
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--muted);
}

.slip-head .stamp {
  color: var(--accent);
  border: 1.5px solid var(--accent);
  border-radius: 4px;
  padding: 0.05rem 0.45rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  transform: rotate(-3deg);
}

.slip pre { border: 0; border-radius: 0; background: transparent; }

.k { color: var(--ink-2); }
.s { color: var(--accent); }
.n { color: var(--ink); }
.c { color: var(--muted); font-style: italic; }

/* Sections */

section { padding: 3rem 0; border-top: 1px solid var(--rule); }

section h2 {
  font-size: clamp(1.5rem, 2.6vw, 2rem);
  letter-spacing: -0.02em;
  line-height: 1.15;
  margin: 0 0 1.2rem;
}

.num {
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--muted);
  letter-spacing: 0.08em;
  display: block;
  margin-bottom: 0.5rem;
}

.prose { max-width: 66ch; }
.prose p { margin: 0 0 1rem; }
.prose ul, .prose ol { padding-left: 1.3rem; margin: 0 0 1rem; }
.prose li { margin-bottom: 0.45rem; }
.prose h3 { font-size: 1.15rem; margin: 2rem 0 0.6rem; letter-spacing: -0.01em; }
.prose pre { margin: 1rem 0 1.4rem; }
.prose table { margin: 1rem 0 1.4rem; }

.cols {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(16rem, 1fr));
  gap: 1.5rem 2.5rem;
}

.cols h3 { margin: 0 0 0.5rem; font-size: 1.1rem; }
.cols p { margin: 0; color: var(--ink-2); }

.steps { counter-reset: step; display: grid; gap: 1.5rem; grid-template-columns: repeat(auto-fit, minmax(17rem, 1fr)); }
.step { position: relative; padding: 1.25rem 1.25rem 1.25rem 3.4rem; background: var(--card); border: 1px solid var(--rule); border-radius: 10px; }
.step::before {
  counter-increment: step;
  content: counter(step);
  position: absolute;
  left: 1.1rem; top: 1.05rem;
  width: 1.7rem; height: 1.7rem;
  border-radius: 50%;
  background: var(--accent);
  color: var(--accent-ink);
  font-family: var(--mono);
  font-weight: 700;
  font-size: 0.85rem;
  display: grid; place-items: center;
}
.step h3 { margin: 0 0 0.4rem; font-size: 1.05rem; }
.step p { margin: 0; color: var(--ink-2); font-size: 0.97rem; }
.step pre { margin-top: 0.8rem; font-size: 0.8rem; }

/* Tables */

.table-wrap { overflow-x: auto; }

table {
  border-collapse: collapse;
  width: 100%;
  font-size: 0.95rem;
}

th, td {
  text-align: left;
  vertical-align: top;
  padding: 0.6rem 0.8rem;
  border-bottom: 1px solid var(--rule);
}

th { font-weight: 600; color: var(--ink-2); font-size: 0.85rem; letter-spacing: 0.03em; text-transform: uppercase; }
td code { white-space: nowrap; }

.lvl {
  display: inline-block;
  font-family: var(--mono);
  font-weight: 700;
  font-size: 0.8rem;
  padding: 0.1rem 0.5rem;
  border-radius: 4px;
  border: 1.5px solid var(--rule);
  color: var(--muted);
}
.lvl.on { border-color: var(--accent); color: var(--accent); }

/* Two-column vendor/consumer */

.split { display: grid; grid-template-columns: repeat(auto-fit, minmax(20rem, 1fr)); gap: 2.5rem; }
.split h3 { margin: 0 0 0.6rem; font-size: 1.25rem; letter-spacing: -0.01em; }
.split p { margin: 0 0 0.8rem; color: var(--ink-2); }
.split pre { margin: 0.8rem 0 1.2rem; }
.split ol { padding-left: 1.3rem; margin: 0.4rem 0 1rem; }
.split li { margin-bottom: 0.4rem; }

.note {
  border-left: 3px solid var(--accent);
  padding: 0.6rem 1rem;
  background: var(--paper-2);
  border-radius: 0 6px 6px 0;
  color: var(--ink-2);
  font-size: 0.95rem;
  margin: 1.2rem 0;
}

/* Footer */

footer {
  border-top: 1px solid var(--rule);
  padding: 2rem 0 3rem;
  color: var(--muted);
  font-size: 0.9rem;
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}
footer nav { display: flex; gap: 1.2rem; flex-wrap: wrap; }
footer a { color: var(--muted); }

/* Spec page */

.doc { display: grid; grid-template-columns: 14rem minmax(0, 1fr); gap: 3rem; padding: 3rem 0 4rem; }
.toc { position: sticky; top: 1.5rem; align-self: start; font-size: 0.92rem; }
.toc ol { list-style: none; padding: 0; margin: 0; }
.toc li { margin: 0.35rem 0; }
.toc a { color: var(--ink-2); text-decoration: none; }
.toc a:hover { color: var(--accent); }
.toc .toc-title { font-family: var(--mono); font-size: 0.75rem; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); margin-bottom: 0.6rem; }

.doc article, .step, .split > div, .cols > div { min-width: 0; }

.doc article h1 { font-size: clamp(2rem, 4vw, 2.8rem); letter-spacing: -0.03em; line-height: 1.1; margin: 0 0 0.6rem; }
.doc article h2 { font-size: 1.5rem; letter-spacing: -0.02em; margin: 2.6rem 0 0.8rem; padding-top: 0.4rem; border-top: 1px solid var(--rule); }
.doc article h2:first-of-type { border-top: 0; margin-top: 1.5rem; }
.doc .meta { color: var(--muted); font-size: 0.95rem; margin-bottom: 1.5rem; }
.doc .meta code { font-size: 0.85rem; }
.req { color: var(--accent); font-weight: 600; font-size: 0.8rem; }
.opt { color: var(--muted); font-size: 0.8rem; }

@media (max-width: 860px) {
  .hero { grid-template-columns: minmax(0, 1fr); gap: 2rem; padding: 3rem 0 2.5rem; }
  .doc { grid-template-columns: minmax(0, 1fr); gap: 1.5rem; }
  .toc { position: static; }
  body { font-size: 16px; }
}

@media (max-width: 600px) {
  #levels td:nth-child(3), #levels th:nth-child(3) { display: none; }
}