:root {
  --ink: #12161c;
  --muted: #5a6573;
  --line: #d5dde6;
  --paper: #f3f6f9;
  --panel: #ffffff;
  --accent: #1f6f7a;
  --accent-soft: #d7eef1;
  --ok: #1f7a4c;
  --warn: #8a5a12;
  --font-display: "Fraunces", "Times New Roman", serif;
  --font-body: "IBM Plex Sans", "Segoe UI", sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, monospace;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  color: var(--ink);
  font-family: var(--font-body);
  background:
    radial-gradient(circle at 10% 0%, #e7f3f5 0%, transparent 40%),
    linear-gradient(180deg, #e9eef3 0%, var(--paper) 50%, #e8edf2 100%);
}

a { color: var(--accent); }
code {
  font-family: var(--font-mono);
  font-size: 0.88em;
  background: var(--accent-soft);
  padding: 0.05em 0.3em;
  border-radius: 2px;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  padding: 0.7rem 1.25rem;
  background: rgba(243, 246, 249, 0.92);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(8px);
}

.topbar a {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  text-decoration: none;
}

.shell {
  width: min(960px, calc(100% - 2rem));
  margin: 0 auto;
  padding: 2rem 0 4rem;
}

.brand {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(2rem, 4vw, 2.8rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.1;
}

.lede {
  margin: 0.75rem 0 0;
  max-width: 40rem;
  color: var(--muted);
  font-size: 1.05rem;
  line-height: 1.5;
}

.tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin: 1.5rem 0 1.25rem;
}

.tabs button {
  appearance: none;
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 0.85rem;
  padding: 0.4rem 0.7rem;
  border-radius: 999px;
  cursor: pointer;
}

.tabs button[aria-selected="true"] {
  background: var(--ink);
  border-color: var(--ink);
  color: #fff;
}

.panel { display: none; }
.panel.active { display: block; }

.stats {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0.75rem;
  margin: 1rem 0 1.25rem;
}

.stat {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 0.85rem 0.9rem;
}

.stat strong {
  display: block;
  font-family: var(--font-display);
  font-size: 1.5rem;
  line-height: 1.1;
}

.stat span {
  color: var(--muted);
  font-size: 0.8rem;
}

.stat.ok strong { color: var(--ok); }

.grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.9rem;
}

.card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 1rem 1.05rem;
}

.card h3 {
  margin: 0 0 0.55rem;
  font-size: 0.95rem;
  font-weight: 600;
}

.card p, .card li {
  color: var(--muted);
  font-size: 0.92rem;
  line-height: 1.45;
}

.card p { margin: 0.35rem 0; }
.card ul { margin: 0.35rem 0 0; padding-left: 1.1rem; }

.callout {
  margin: 1rem 0;
  padding: 0.9rem 1rem;
  border-left: 3px solid var(--accent);
  background: var(--accent-soft);
  border-radius: 0 4px 4px 0;
}

.callout.warn {
  border-left-color: var(--warn);
  background: #f7efdf;
}

.callout h3 {
  margin: 0 0 0.35rem;
  font-size: 0.95rem;
}

.callout p { margin: 0; color: var(--ink); font-size: 0.92rem; line-height: 1.45; }

h2 {
  margin: 1.5rem 0 0.6rem;
  font-family: var(--font-display);
  font-size: 1.45rem;
}

h3.section {
  margin: 1.2rem 0 0.5rem;
  font-size: 1.05rem;
}

table {
  width: 100%;
  border-collapse: collapse;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 4px;
  overflow: hidden;
  font-size: 0.88rem;
  margin: 0.6rem 0 1rem;
}

th, td {
  text-align: left;
  padding: 0.55rem 0.7rem;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}

th {
  background: #e8eef3;
  font-weight: 600;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  color: var(--muted);
}

tr:last-child td { border-bottom: none; }
td.up { color: var(--ok); font-family: var(--font-mono); font-size: 0.8rem; }

.flow {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
  align-items: center;
  margin: 0.75rem 0 1rem;
}

.flow .node {
  background: var(--panel);
  border: 1px solid var(--line);
  padding: 0.4rem 0.65rem;
  border-radius: 4px;
  font-size: 0.85rem;
}

.flow .node.hot {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.flow .arrow {
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: 0.8rem;
}

.caption {
  color: var(--muted);
  font-size: 0.8rem;
  margin-top: 0.75rem;
}

@media (max-width: 800px) {
  .stats { grid-template-columns: 1fr 1fr; }
  .grid-2 { grid-template-columns: 1fr; }
}

@media (max-width: 520px) {
  .stats { grid-template-columns: 1fr; }
  .shell { width: min(100% - 1.25rem, 960px); }
}