*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg:          #0c0e12;
  --bg-sidebar:  #080a0d;
  --bg-code:     #111318;
  --border:      #1c1f28;
  --text:        #b2b6c4;
  --text-dim:    #585d70;
  --heading:     #e4e7f2;
  --accent:      #20d4a0;
  --accent-dim:  rgba(32, 212, 160, 0.08);
  --sidebar-w:   260px;
  --font-body:   system-ui, -apple-system, sans-serif;
  --font-mono:   ui-monospace, 'SF Mono', 'Cascadia Code', monospace;
}

html { font-size: 16px; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  line-height: 1.7;
  display: flex;
  min-height: 100vh;
}

/* ── Sidebar ── */

nav {
  width: var(--sidebar-w);
  min-height: 100vh;
  background: var(--bg-sidebar);
  border-right: 1px solid var(--border);
  padding: 1.75rem 0;
  position: sticky;
  top: 0;
  overflow-y: auto;
  flex-shrink: 0;
}

.brand {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  padding: 0 1.25rem 1.5rem;
  border-bottom: 1px solid var(--border);
  display: block;
  text-decoration: none;
}

.nav-section { padding: 1.25rem 0 0; }

.nav-label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-dim);
  padding: 0 1.25rem 0.5rem;
  display: block;
}

.nav-section a {
  display: block;
  font-size: 0.875rem;
  color: var(--text);
  text-decoration: none;
  padding: 0.35rem 1.25rem;
  transition: color 0.1s;
}

.nav-section a:hover { color: var(--heading); }

.nav-section a.active {
  color: var(--accent);
  background: var(--accent-dim);
  border-right: 2px solid var(--accent);
}

/* ── Main ── */

main {
  flex: 1;
  max-width: 760px;
  padding: 3rem 3.5rem 6rem;
}

/* ── Typography ── */

h1 {
  font-family: var(--font-mono);
  font-size: 1.75rem;
  font-weight: 600;
  color: var(--heading);
  letter-spacing: -0.02em;
  margin-bottom: 0.5rem;
}

h2 {
  font-family: var(--font-mono);
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--heading);
  margin: 2.5rem 0 0.75rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border);
}

h3 {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--heading);
  margin: 1.75rem 0 0.5rem;
  font-family: var(--font-mono);
}

p { margin-bottom: 1rem; }

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.subtitle {
  color: var(--text-dim);
  font-size: 1rem;
  margin-bottom: 2rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--border);
}

/* ── Code ── */

code {
  font-family: var(--font-mono);
  font-size: 0.82em;
  background: var(--bg-code);
  color: #e0e4f0;
  padding: 0.15em 0.4em;
  border-radius: 3px;
  border: 1px solid var(--border);
}

pre {
  background: var(--bg-code);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 1.25rem 1.5rem;
  overflow-x: auto;
  margin: 1rem 0 1.5rem;
}

pre code {
  background: none;
  border: none;
  padding: 0;
  font-size: 0.85rem;
  line-height: 1.6;
  color: #c8ccd8;
}

/* YAML token spans — hand-applied in markup */
.k { color: #7db8e8; }   /* key   */
.s { color: #98d982; }   /* string value */
.n { color: #e0b87a; }   /* number */
.c { color: #505568; font-style: italic; } /* comment */

/* ── Callout ── */

.callout {
  border-left: 3px solid var(--accent);
  background: var(--accent-dim);
  border-radius: 0 4px 4px 0;
  padding: 0.75rem 1rem;
  margin: 1.25rem 0;
  font-size: 0.9rem;
}

.callout strong { color: var(--heading); }

/* ── Page nav ── */

.page-nav {
  display: flex;
  justify-content: space-between;
  margin-top: 4rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  font-size: 0.875rem;
}

.page-nav a { color: var(--text-dim); }
.page-nav a:hover { color: var(--accent); }
.page-nav .next { text-align: right; }
.page-nav .label { display: block; font-size: 0.75rem; margin-bottom: 0.25rem; }

/* ── Mobile ── */

@media (max-width: 720px) {
  body { flex-direction: column; }

  nav {
    width: 100%;
    min-height: auto;
    position: static;
    border-right: none;
    border-bottom: 1px solid var(--border);
    padding: 1rem 0;
  }

  main { padding: 2rem 1.25rem 4rem; }
}