:root {
  color-scheme: dark;
  --bg: #0f1c28;
  --panel: #182b3b;
  --panel2: #20394c;
  --ink: #eef4f6;
  --muted: #acc0cc;
  --line: #3f5a6b;
  --accent: #6fe0d1;
  --violet: #b9a3ff;
  --amber: #ffc47d;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: radial-gradient(circle at 80% 0%, #1b3546 0, var(--bg) 42%);
  color: var(--ink);
  font: 15px/1.55 system-ui, -apple-system, sans-serif;
}

.shell {
  max-width: 1180px;
  margin: auto;
  padding: 24px;
}

.site-header {
  border-bottom: 1px solid var(--line);
  padding-bottom: 18px;
}

.brand-row {
  align-items: center;
  display: flex;
  justify-content: space-between;
  gap: 16px;
}

.brand {
  align-items: center;
  color: var(--ink);
  display: flex;
  font-weight: 700;
  gap: 10px;
  text-decoration: none;
}

.brand-mark {
  align-items: center;
  background: var(--accent);
  border-radius: 10px;
  color: #10222c;
  display: flex;
  font-size: 22px;
  height: 38px;
  justify-content: center;
  width: 38px;
}

.author,
.card p,
.panel p,
.lead,
.breadcrumbs,
.notice,
footer {
  color: var(--muted);
}

.author {
  font-size: 12px;
}

.global-nav,
.topic-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  margin-top: 16px;
}

.global-nav a,
.topic-nav a {
  border: 1px solid var(--line);
  border-radius: 8px;
  color: var(--muted);
  font-size: 12px;
  padding: 7px 10px;
  text-decoration: none;
}

.global-nav a:hover,
.global-nav a:focus-visible,
.topic-nav a:hover,
.topic-nav a:focus-visible,
.global-nav a[aria-current="page"],
.topic-nav a[aria-current="page"] {
  border-color: var(--accent);
  color: var(--ink);
}

main {
  padding: 30px 0;
}

.breadcrumbs {
  font-size: 13px;
  margin-top: 18px;
}

.breadcrumbs a {
  color: var(--accent);
}

.eyebrow {
  color: var(--accent);
  font-size: 11px;
  letter-spacing: 2px;
  margin: 0 0 10px;
  text-transform: uppercase;
}

h1 {
  font-size: clamp(30px, 5vw, 54px);
  line-height: 1.05;
  margin: 0 0 12px;
  max-width: 800px;
}

h2 {
  font-size: 24px;
  margin: 0 0 8px;
}

.lead {
  font-size: 17px;
  max-width: 700px;
}

.choices,
.panel-grid {
  display: grid;
  gap: 16px;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin-top: 30px;
}

.card {
  background: linear-gradient(145deg, var(--panel2), var(--panel));
  border: 1px solid var(--line);
  border-radius: 16px;
  color: var(--ink);
  display: block;
  padding: 20px;
  text-decoration: none;
  transition: border-color 0.15s, transform 0.15s;
}

.card:hover,
.card:focus-visible {
  border-color: var(--accent);
  transform: translateY(-2px);
}

.card p,
.panel p {
  margin: 5px 0;
}

.card h2 {
  text-align: center;
}

.mini {
  height: 110px;
  margin-bottom: 12px;
  width: 100%;
}

.mini path,
.mini line {
  fill: none;
  stroke: #dce8eb;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-width: 3;
}

.mini .accent {
  stroke: var(--accent);
}

.mini .violet {
  stroke: var(--violet);
}

.mini .transistor-circle {
  fill: none;
  stroke: var(--accent);
  stroke-width: 3;
}

.mini .icon-label {
  fill: var(--ink);
  font-size: 24px;
  font-weight: 700;
  stroke: none;
}

.panel {
  background: rgba(24, 43, 59, 0.86);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 18px;
}

.button-link {
  background: var(--accent);
  border-radius: 8px;
  color: #10222c;
  display: inline-block;
  font-weight: 700;
  margin-top: 12px;
  padding: 9px 13px;
  text-decoration: none;
}

.button-link:hover,
.button-link:focus-visible {
  background: #a2f3e8;
}

.notice {
  border-left: 3px solid var(--amber);
  font-size: 13px;
  margin-top: 18px;
  padding: 8px 12px;
}

footer {
  border-top: 1px solid var(--line);
  font-size: 12px;
  padding: 16px 0;
  text-align: center;
}

.identity-footer p {
  margin: 3px 0;
}

@media (max-width: 720px) {
  .shell {
    padding: 16px;
  }

  .choices,
  .panel-grid {
    grid-template-columns: 1fr;
  }

  .brand-row {
    align-items: flex-start;
    flex-direction: column;
  }

  main {
    padding-top: 22px;
  }
}