:root {
  color-scheme: light dark;
  --background: #f7f8fa;
  --surface: #ffffff;
  --text: #18202b;
  --muted: #5c6776;
  --border: #d9dee7;
  --accent: #165dba;
  --accent-hover: #0d4389;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.55;
}

* { box-sizing: border-box; }
body { margin: 0; color: var(--text); background: var(--background); }
a { color: var(--accent); text-underline-offset: 0.18em; }
a:hover { color: var(--accent-hover); }
.site-header, main, footer { width: min(70rem, calc(100% - 2rem)); margin-inline: auto; }
.site-header { display: flex; align-items: center; justify-content: space-between; min-height: 4.5rem; border-bottom: 1px solid var(--border); }
.brand { display: flex; align-items: center; gap: 0.65rem; color: var(--text); font-size: 1.35rem; font-weight: 750; text-decoration: none; }
.site-header nav { display: flex; gap: 1.25rem; }
.site-header nav a { font-weight: 650; }
main { min-height: calc(100vh - 10rem); padding-block: 3rem 4rem; }
footer { padding-block: 1.25rem 2.5rem; color: var(--muted); border-top: 1px solid var(--border); }
h1, h2, h3 { line-height: 1.2; }
h1 { margin: 0 0 1rem; font-size: clamp(2rem, 5vw, 3.25rem); letter-spacing: -0.035em; }
h2 { margin-top: 3rem; font-size: 1.6rem; }
.hero { max-width: 48rem; }
.port-lookup { display: grid; grid-template-columns: 10rem minmax(12rem, 1fr) auto; gap: 0.8rem; align-items: end; margin-top: 2rem; padding: 1.25rem; background: var(--surface); border: 1px solid var(--border); border-radius: 0.75rem; }
label span { display: block; margin-bottom: 0.35rem; color: var(--muted); font-size: 0.88rem; font-weight: 650; }
input, select, button { width: 100%; min-height: 2.8rem; padding: 0.6rem 0.75rem; border: 1px solid var(--border); border-radius: 0.4rem; font: inherit; }
button { color: white; background: var(--accent); border-color: var(--accent); cursor: pointer; font-weight: 700; }
button:hover { background: var(--accent-hover); }
.protocol-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1rem; }
.protocol-card { display: flex; flex-direction: column; gap: 0.25rem; padding: 1.2rem; color: var(--text); background: var(--surface); border: 1px solid var(--border); border-radius: 0.65rem; text-decoration: none; }
.protocol-card:hover { border-color: var(--accent); }
.protocol-card strong { font-size: 1.15rem; }
.protocol-card span { color: var(--muted); }
.breadcrumbs { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-bottom: 1.5rem; color: var(--muted); font-size: 0.92rem; }
.port-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(6rem, 1fr)); gap: 0.55rem; padding: 0; list-style: none; }
.port-grid a { display: block; padding: 0.6rem 0.7rem; background: var(--surface); border: 1px solid var(--border); border-radius: 0.35rem; text-align: center; text-decoration: none; }
.pagination { display: grid; grid-template-columns: 1fr auto 1fr; align-items: center; gap: 1rem; margin-top: 2rem; }
.pagination a:last-child { text-align: right; }
.prose { max-width: 48rem; font-size: 1.05rem; }
.prose h2 { margin-top: 2.5rem; }

@media (prefers-color-scheme: dark) {
  :root { --background: #11151b; --surface: #191f28; --text: #eef2f7; --muted: #aab4c2; --border: #303946; --accent: #77adf2; --accent-hover: #a7caff; }
  button { color: #101722; background: #77adf2; }
}

@media (max-width: 42rem) {
  .site-header, main, footer { width: min(100% - 1.25rem, 70rem); }
  main { padding-top: 2rem; }
  .port-lookup { grid-template-columns: 1fr; }
  .protocol-grid { grid-template-columns: 1fr; }
  .pagination { grid-template-columns: 1fr 1fr; }
  .pagination span { grid-column: 1 / -1; grid-row: 1; text-align: center; }
}