:root {
  --bg-0: #f3efe5;
  --bg-1: #f7f4ec;
  --ink: #231b16;
  --muted: #61564c;
  --line: #cbbda9;
  --line-strong: #9f8d78;
  --panel: rgba(247, 242, 232, 0.82);
  --panel-alt: rgba(235, 226, 209, 0.72);
  --accent: #7c2f18;
  --accent-ink: #ffffff;
  --mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  --sans: "IBM Plex Sans", "Segoe UI", sans-serif;
  --max: 1160px;
  --shadow: 0 24px 70px rgba(53, 32, 20, 0.14);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--sans);
  color: var(--ink);
  line-height: 1.55;
  background:
    radial-gradient(72rem 42rem at 12% -8%, #fff8e8 0%, transparent 62%),
    radial-gradient(54rem 30rem at 100% 14%, #eed9ba 0%, transparent 66%),
    linear-gradient(180deg, var(--bg-1) 0%, var(--bg-0) 60%, #efe7d8 100%);
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  opacity: 0.16;
  background-image:
    linear-gradient(rgba(124, 47, 24, 0.08) 1px, transparent 1px),
    linear-gradient(90deg, rgba(124, 47, 24, 0.08) 1px, transparent 1px);
  background-size: 18px 18px;
  mask-image: linear-gradient(180deg, #000 24%, transparent 96%);
}

a {
  color: inherit;
}

.shell {
  width: min(calc(100% - 2.2rem), var(--max));
  margin: 0 auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  border-bottom: 1px solid rgba(159, 141, 120, 0.5);
  background: rgba(249, 244, 236, 0.86);
  backdrop-filter: blur(12px);
}

.nav-shell {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.45rem;
  padding: 1.2rem 0;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.78rem;
  text-decoration: none;
  font-weight: 700;
  font-size: 1.08rem;
  letter-spacing: 0.01em;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 2.45rem;
  height: 2.45rem;
  border-radius: 0.65rem;
  border: 1px solid var(--line-strong);
  background: linear-gradient(135deg, #f1dfc2, #e6c99d);
  overflow: hidden;
  padding: 0;
}

.brand-mark img {
  width: 120%;
  height: 120%;
  display: block;
  object-fit: cover;
  object-position: center;
  border-radius: 0.58rem;
}

.nav-links {
  display: flex;
  gap: 1.1rem;
  flex-wrap: wrap;
}

.nav-links a {
  text-decoration: none;
  font-size: 1rem;
  color: var(--muted);
  border-bottom: 1px solid transparent;
  transition: color 120ms ease, border-color 120ms ease;
}

.nav-links a:hover {
  color: var(--ink);
  border-color: var(--line-strong);
}

.section {
  padding: clamp(2rem, 5vw, 4rem) 0;
}

.hero {
  padding-top: clamp(2.4rem, 6vw, 5rem);
}

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

.panel {
  border: 1px solid rgba(159, 141, 120, 0.6);
  border-radius: 1.1rem;
  background: var(--panel);
  box-shadow: var(--shadow);
  padding: 1.15rem 1.15rem 1.2rem;
  backdrop-filter: blur(12px);
}

.panel-dense {
  background: var(--panel-alt);
}

.kicker {
  margin: 0 0 0.55rem;
  font-family: var(--mono);
  font-size: 0.76rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
}

h1,
h2,
h3 {
  margin: 0 0 0.7rem;
  line-height: 1.12;
  letter-spacing: -0.02em;
}

h1 {
  font-size: clamp(2rem, 5vw, 3.6rem);
}

h2 {
  font-size: clamp(1.55rem, 3.5vw, 2.2rem);
}

h3 {
  font-size: 1.12rem;
}

p {
  margin: 0 0 0.72rem;
}

.lead {
  max-width: 62ch;
  color: #3f362f;
}

.who-for {
  margin-top: 0.45rem;
  border: 1px solid rgba(159, 141, 120, 0.52);
  border-radius: 0.8rem;
  background: rgba(255, 255, 255, 0.57);
  padding: 0.66rem 0.72rem 0.62rem;
}

.who-for-title {
  margin: 0 0 0.24rem;
  font-family: var(--mono);
  font-size: 0.76rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--muted);
}

.who-for-copy {
  margin: 0;
  color: #3f362f;
}

.section-head p {
  color: var(--muted);
  max-width: 74ch;
}

.cta-row,
.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.62rem;
  margin: 0.85rem 0 0;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 0.8rem;
  border: 1px solid var(--line-strong);
  text-decoration: none;
  font-weight: 600;
  padding: 0.62rem 0.82rem;
  font-size: 0.94rem;
  cursor: pointer;
  transition: transform 140ms ease, background 140ms ease;
}

.btn:hover {
  transform: translateY(-1px);
}

.btn-primary {
  background: linear-gradient(135deg, #7c2f18, #9d3f22);
  border-color: #5f2412;
  color: var(--accent-ink);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.5);
  color: var(--ink);
}

.quick-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.5rem;
  margin-top: 0.9rem;
}

.quick-grid > div {
  border: 1px solid rgba(159, 141, 120, 0.52);
  border-radius: 0.8rem;
  background: rgba(255, 255, 255, 0.58);
  padding: 0.6rem 0.7rem;
}

.quick-label {
  display: block;
  margin-bottom: 0.25rem;
  font-size: 0.78rem;
  color: var(--muted);
}

code,
.code {
  font-family: var(--mono);
}

code {
  font-size: 0.88em;
  background: rgba(255, 255, 255, 0.62);
  border: 1px solid rgba(159, 141, 120, 0.5);
  border-radius: 0.32rem;
  padding: 0.05rem 0.26rem;
}

ul {
  margin: 0.25rem 0 0.65rem 1.1rem;
  padding: 0;
}

li {
  margin: 0.26rem 0;
}

.playground {
  display: grid;
  gap: 0.42rem;
}

.playground label {
  margin-top: 0.28rem;
  font-size: 0.87rem;
  color: var(--muted);
}

.playground input {
  width: 100%;
  font: inherit;
  color: var(--ink);
  padding: 0.6rem 0.68rem;
  border-radius: 0.7rem;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.62);
}

.meta-line {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--muted);
  margin-top: 0.8rem;
}

.rfc-meta-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.28rem 0.9rem;
}

.rfc-meta-grid p {
  margin: 0;
}

.rfc-toc-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.4rem 0.85rem;
}

.rfc-toc-grid a {
  display: inline-block;
  text-decoration: none;
  color: var(--muted);
  border-bottom: 1px solid rgba(159, 141, 120, 0.44);
  padding-bottom: 0.1rem;
  font-family: var(--mono);
  font-size: 0.83rem;
}

.rfc-toc-grid a:hover {
  color: var(--ink);
}

.rfc-grid {
  margin-top: 0.25rem;
}

.rfc-card {
  border: 1px solid rgba(159, 141, 120, 0.52);
  border-radius: 0.8rem;
  background: rgba(255, 255, 255, 0.55);
  padding: 0.72rem;
}

.rfc-card p {
  margin: 0 0 0.5rem;
}

.rfc-journey p {
  margin-bottom: 0.42rem;
}

.rfc-note {
  border: 1px solid rgba(159, 141, 120, 0.6);
  border-left: 4px solid #9d3f22;
  border-radius: 0.7rem;
  background: rgba(255, 255, 255, 0.56);
  padding: 0.68rem 0.72rem 0.58rem;
  margin-bottom: 0.75rem;
}

.rfc-note p {
  margin: 0 0 0.4rem;
}

.rfc-note p:last-child {
  margin-bottom: 0;
}

.rfc-note-warn {
  border-left-color: #735d42;
}

.table-wrap {
  width: 100%;
  overflow-x: auto;
}

.data-table {
  width: 100%;
  border-collapse: collapse;
  min-width: 620px;
}

.data-table th,
.data-table td {
  border: 1px solid rgba(159, 141, 120, 0.55);
  padding: 0.56rem 0.62rem;
  text-align: left;
  vertical-align: top;
  font-size: 0.93rem;
}

.data-table th {
  background: rgba(236, 223, 203, 0.72);
  font-family: var(--mono);
  font-size: 0.75rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.code {
  border-radius: 0.8rem;
  border: 1px solid rgba(159, 141, 120, 0.5);
  padding: 0.75rem;
  background: #f7f0e3;
  font-size: 0.84rem;
  line-height: 1.45;
  margin-top: 0.8rem;
  overflow: auto;
}

.code-scroll {
  max-height: 290px;
}

.topology-grid {
  display: grid;
  grid-template-columns: 1fr 40px 1fr 40px 1fr 40px 1fr;
  align-items: stretch;
  gap: 0;
  min-width: 860px;
}

.node {
  border: 1px solid rgba(159, 141, 120, 0.62);
  border-radius: 0.8rem;
  padding: 0.7rem;
  background: rgba(255, 255, 255, 0.55);
}

.node.active {
  border-color: #7c2f18;
  box-shadow: inset 0 0 0 1px #7c2f18;
}

.node-domain {
  margin: 0 0 0.42rem;
  font-family: var(--mono);
  font-size: 0.75rem;
  color: var(--muted);
}

.node-title {
  margin: 0 0 0.42rem;
  font-weight: 700;
}

.node-copy {
  margin: 0;
  font-size: 0.89rem;
  color: #4c433b;
}

.arrow {
  display: grid;
  place-items: center;
  font-size: 1.2rem;
  color: var(--muted);
}

.site-footer {
  border-top: 1px solid rgba(159, 141, 120, 0.56);
  padding: 1.1rem 0 1.4rem;
  background: rgba(248, 240, 226, 0.7);
}

.footer-shell {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 0.7rem;
  color: var(--muted);
  font-size: 0.86rem;
}

.reveal {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 400ms ease, transform 450ms ease;
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

@media (max-width: 1020px) {
  .hero-grid,
  .grid-2 {
    grid-template-columns: 1fr;
  }

  .topology-grid {
    grid-template-columns: 1fr;
    min-width: 0;
    gap: 0.42rem;
  }

  .arrow {
    transform: rotate(90deg);
  }
}

@media (max-width: 760px) {
  .quick-grid {
    grid-template-columns: 1fr;
  }

  .rfc-meta-grid,
  .rfc-toc-grid {
    grid-template-columns: 1fr;
  }

  .nav-shell {
    align-items: flex-start;
    flex-direction: column;
    gap: 0.9rem;
    padding: 0.95rem 0;
  }

  .brand {
    font-size: 1rem;
  }

  .brand-mark {
    width: 2.2rem;
    height: 2.2rem;
  }

  .nav-links a {
    font-size: 0.95rem;
  }
}