/* ============================================================
   NCC 2022 Quick Reference — Shared Stylesheet
   Edit tokens in :root to retheme the whole site at once.
   ============================================================ */

:root {
  /* Colour tokens */
  --bg:        #ECEEF1;   /* drafting paper */
  --surface:   #FBFBF9;   /* card / page surface */
  --ink:       #0E1722;   /* deep navy-black for text */
  --ink-mute:  #545C68;   /* secondary text */
  --rule:      #0E1722;   /* hairline */
  --rule-soft: #C8CDD4;   /* soft divider */
  --accent:    #1E4F87;   /* drafting blue — links, anchors */
  --stamp:     #B5321C;   /* regulation red — used sparingly for emphasis */
  --focus:     #1E4F87;

  /* Type */
  --font-display: "Space Grotesk", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-body:    "Inter", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono:    "JetBrains Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;

  /* Scale */
  --maxw: 1180px;
  --gutter: clamp(1.25rem, 4vw, 2.5rem);
}

/* Reset-ish */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img { max-width: 100%; display: block; }

a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid currentColor;
  transition: opacity 0.15s ease;
}
a:hover { opacity: 0.7; }
a:focus-visible {
  outline: 2px solid var(--focus);
  outline-offset: 3px;
  border-radius: 2px;
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

/* ============================================================
   Layout primitives
   ============================================================ */

.shell {
  max-width: var(--maxw);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

/* ============================================================
   Top bar
   ============================================================ */

.topbar {
  border-bottom: 1px solid var(--rule);
  background: var(--bg);
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: blur(6px);
  background: rgba(236, 238, 241, 0.85);
}

.topbar__inner {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  padding-block: 1rem;
}

.brand {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.05rem;
  letter-spacing: -0.01em;
  color: var(--ink);
  border-bottom: none;
}
.brand span {
  font-family: var(--font-mono);
  font-weight: 600;
  color: var(--stamp);
  margin-right: 0.4em;
}

.topbar__meta {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--ink-mute);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

/* ============================================================
   Hero / intro
   ============================================================ */

.hero {
  padding-block: clamp(3rem, 7vw, 5.5rem) clamp(2rem, 4vw, 3rem);
  border-bottom: 1px solid var(--rule-soft);
}

.hero__eyebrow {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-mute);
  margin: 0 0 1rem;
}

.hero h1 {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(2rem, 5.5vw, 3.6rem);
  line-height: 1.05;
  letter-spacing: -0.02em;
  margin: 0 0 1.2rem;
  max-width: 22ch;
}

.hero p {
  max-width: 56ch;
  color: var(--ink-mute);
  font-size: clamp(1rem, 1.6vw, 1.1rem);
  margin: 0;
}

/* ============================================================
   Topic grid (homepage)
   ============================================================ */

.topics {
  padding-block: clamp(2.5rem, 5vw, 4rem) clamp(3rem, 6vw, 5rem);
}

.topics__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 2rem;
  border-bottom: 1px solid var(--rule);
  padding-bottom: 0.6rem;
}

.topics__head h2 {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.05rem;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  margin: 0;
}

.topics__head span {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--ink-mute);
  letter-spacing: 0.04em;
}

.topic-grid {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1px;
  background: var(--rule);
  border: 1px solid var(--rule);
}

.topic {
  background: var(--surface);
  position: relative;
}

.topic__link {
  display: flex;
  flex-direction: column;
  height: 100%;
  padding: 1.75rem 1.5rem 1.4rem;
  color: var(--ink);
  border-bottom: none;
  transition: background-color 0.18s ease;
}

.topic__link:hover {
  background: #F4F5F6;
  opacity: 1;
}

.topic__num {
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: clamp(2.6rem, 5vw, 3.4rem);
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--ink);
  margin: 0 0 1.5rem;
  display: block;
}

.topic__title {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.2rem;
  line-height: 1.2;
  margin: 0 0 0.5rem;
  letter-spacing: -0.01em;
}

.topic__desc {
  color: var(--ink-mute);
  font-size: 0.92rem;
  line-height: 1.5;
  margin: 0 0 1.5rem;
  flex-grow: 1;
}

.topic__foot {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-mute);
  padding-top: 1rem;
  border-top: 1px solid var(--rule-soft);
}

.topic__foot .arrow {
  font-family: var(--font-body);
  font-size: 1rem;
  color: var(--accent);
}

/* ============================================================
   Inner pages
   ============================================================ */

.crumb {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-mute);
  margin-bottom: 1.4rem;
  display: inline-block;
  border-bottom: none;
}
.crumb:hover { color: var(--accent); }

.page-head {
  padding-block: clamp(2.5rem, 5vw, 4rem) clamp(1.5rem, 3vw, 2.5rem);
  border-bottom: 1px solid var(--rule);
}

.page-head__num {
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: clamp(3.5rem, 9vw, 6rem);
  line-height: 1;
  letter-spacing: -0.04em;
  color: var(--ink);
  margin: 0 0 1rem;
  display: block;
}

.page-head h1 {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(1.75rem, 4vw, 2.6rem);
  line-height: 1.1;
  letter-spacing: -0.02em;
  margin: 0 0 0.8rem;
}

.page-head .lede {
  max-width: 60ch;
  color: var(--ink-mute);
  font-size: 1.05rem;
  margin: 0;
}

.page-body {
  padding-block: clamp(2.5rem, 5vw, 4rem);
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(2.5rem, 4vw, 3.5rem);
}

@media (min-width: 900px) {
  .page-body { grid-template-columns: 1fr 280px; }
}

.page-section h2 {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.4rem;
  letter-spacing: -0.01em;
  margin: 0 0 0.5rem;
  padding-bottom: 0.4rem;
  border-bottom: 1px solid var(--rule);
}

.page-section h2 .num {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--stamp);
  margin-right: 0.6rem;
  letter-spacing: 0.04em;
}

.page-section + .page-section { margin-top: 2.5rem; }

.page-section p, .page-section li {
  color: var(--ink);
  line-height: 1.65;
}

.page-section ul, .page-section ol {
  padding-left: 1.2rem;
}

.todo {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--stamp);
  background: rgba(181, 50, 28, 0.08);
  padding: 0.2rem 0.5rem;
  margin-left: 0.5rem;
  border: 1px solid rgba(181, 50, 28, 0.3);
}

/* Sidebar */
.sidebar {
  font-size: 0.93rem;
}

.sidebar__block {
  border-top: 1px solid var(--rule);
  padding-top: 1rem;
  margin-bottom: 1.8rem;
}

.sidebar__label {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-mute);
  margin: 0 0 0.6rem;
}

.sidebar ul {
  list-style: none;
  padding: 0;
  margin: 0;
}
.sidebar li + li { margin-top: 0.4rem; }

/* ============================================================
   Footer
   ============================================================ */

.foot {
  border-top: 1px solid var(--rule);
  padding-block: 2rem 2.5rem;
  font-size: 0.88rem;
  color: var(--ink-mute);
}

.foot__inner {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
  justify-content: space-between;
  align-items: baseline;
}

.foot a { color: var(--ink-mute); }
.foot a:hover { color: var(--accent); }

.foot__note {
  max-width: 60ch;
  font-size: 0.82rem;
}

/* ============================================================
   Utility
   ============================================================ */

.divider {
  height: 1px;
  background: var(--rule-soft);
  border: none;
  margin: 2rem 0;
}