:root {
  color-scheme: light;
  --ink: #1d252c;
  --muted: #52616b;
  --line: #d8dee4;
  --paper: #fbfcfd;
  --panel: #ffffff;
  --accent: #0f7b8c;
  --accent-strong: #075c69;
  --warm: #f4b942;
  --button-ink: #ffffff;
  --topbar-bg: rgba(251, 252, 253, 0.94);
  --code-bg: #111920;
  --code-ink: #e8f2f4;
  --quote-bg: #fff8e6;
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --ink: #edf4f7;
  --muted: #adc0ca;
  --line: #2f3b42;
  --paper: #101416;
  --panel: #181f22;
  --accent: #58c4d4;
  --accent-strong: #8ddfed;
  --warm: #f6c661;
  --button-ink: #0d1518;
  --topbar-bg: rgba(16, 20, 22, 0.94);
  --code-bg: #0b1114;
  --code-ink: #eef8fb;
  --quote-bg: #221f15;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--ink);
  background: var(--paper);
  line-height: 1.6;
}

a { color: var(--accent-strong); }

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 14px 28px;
  border-bottom: 1px solid var(--line);
  background: var(--topbar-bg);
  backdrop-filter: blur(12px);
}

.brand {
  color: var(--ink);
  font-weight: 760;
  text-decoration: none;
}

.topbar nav {
  display: flex;
  align-items: center;
  gap: 16px;
  font-size: 14px;
}

.topbar a { text-decoration: none; }

.nav-action,
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 38px;
  padding: 0 14px;
  border: 1px solid var(--accent);
  background: var(--accent);
  color: var(--button-ink);
  text-decoration: none;
  font-weight: 650;
}

.button.secondary {
  background: transparent;
  color: var(--accent-strong);
}

.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-width: 92px;
  min-height: 38px;
  padding: 0 12px;
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--ink);
  cursor: pointer;
  font: inherit;
  font-weight: 650;
}

.theme-toggle-indicator {
  position: relative;
  width: 34px;
  height: 18px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--paper);
  flex: 0 0 auto;
}

.theme-toggle-indicator::after {
  position: absolute;
  top: 3px;
  left: 3px;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--accent);
  content: "";
  transition: transform 160ms ease;
}

:root[data-theme="dark"] .theme-toggle-indicator::after {
  transform: translateX(16px);
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) minmax(320px, 0.9fr);
  align-items: center;
  gap: 40px;
  max-width: 1160px;
  min-height: calc(100vh - 68px);
  margin: 0 auto;
  padding: 64px 28px;
}

.eyebrow {
  margin: 0 0 16px;
  color: var(--accent-strong);
  font-weight: 760;
  text-transform: uppercase;
  font-size: 13px;
}

h1 {
  max-width: 760px;
  margin: 0;
  font-size: clamp(42px, 7vw, 80px);
  line-height: 0.98;
}

.hero p {
  max-width: 680px;
  color: var(--muted);
  font-size: 18px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

.terminal-panel {
  border: 1px solid #26343d;
  background: #111920;
  color: #e8f2f4;
  min-height: 320px;
  padding: 18px;
}

.terminal-panel span {
  display: block;
  margin-bottom: 24px;
  color: var(--warm);
  font-weight: 700;
}

pre {
  overflow: auto;
  padding: 16px;
  background: var(--code-bg);
  color: var(--code-ink);
}

code {
  font-family: "Cascadia Code", Consolas, monospace;
  font-size: 0.94em;
}

.band,
.lessons {
  max-width: 1160px;
  margin: 0 auto;
  padding: 42px 28px;
}

.steps {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
}

.steps div,
.lesson-card {
  border: 1px solid var(--line);
  background: var(--panel);
  padding: 18px;
}

.steps strong {
  display: inline-grid;
  place-items: center;
  width: 32px;
  height: 32px;
  margin-bottom: 10px;
  background: var(--warm);
}

.note {
  margin-top: 18px;
  color: var(--muted);
}

.lesson-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 16px;
}

.lesson-card h3 {
  margin: 0 0 8px;
}

.lesson-card p {
  min-height: 44px;
  color: var(--muted);
  font-size: 14px;
}

.lesson-card div {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.layout {
  display: grid;
  grid-template-columns: 260px minmax(0, 1fr);
  max-width: 1240px;
  margin: 0 auto;
}

.sidebar {
  position: sticky;
  top: 67px;
  height: calc(100vh - 67px);
  overflow: auto;
  padding: 28px 18px;
  border-right: 1px solid var(--line);
}

.sidebar nav {
  display: grid;
  gap: 8px;
  margin-top: 12px;
}

.sidebar a {
  text-decoration: none;
}

.content {
  max-width: 860px;
  padding: 36px 32px 80px;
}

.page-actions {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 24px;
  color: var(--muted);
  font-size: 14px;
}

.content h1,
.content h2,
.content h3 {
  line-height: 1.18;
}

.content h1 {
  font-size: 42px;
}

.content h2 {
  margin-top: 36px;
}

.content table {
  width: 100%;
  border-collapse: collapse;
}

.content th,
.content td {
  border: 1px solid var(--line);
  padding: 8px;
  text-align: left;
}

blockquote {
  margin: 18px 0;
  padding: 1px 18px;
  border-left: 4px solid var(--warm);
  background: var(--quote-bg);
}

@media (max-width: 820px) {
  .topbar,
  .topbar nav,
  .page-actions {
    align-items: flex-start;
    flex-direction: column;
  }

  .hero,
  .layout,
  .steps {
    grid-template-columns: 1fr;
  }

  .hero {
    min-height: auto;
  }

  .sidebar {
    position: static;
    height: auto;
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }
}