/* ═══════════════════════════════════════════
   PROMPT ENGINES LAB NOTES
   taste-skill compliant · design-variance:8
   motion-intensity:6 · visual-density:4
   ═══════════════════════════════════════════ */

:root {
  --bg: #09090b;
  --bg-elevated: #18181b;
  --bg-subtle: #0f0f12;
  --border: #27272a;
  --border-subtle: rgba(255, 255, 255, 0.06);
  --text: #fafafa;
  --text-2: #d4d4d8;
  --text-3: #a1a1aa;
  --text-4: #71717a;
  --accent: #F04D26;
  --accent-hover: #d94420;
  --accent-dim: rgba(240, 77, 38, 0.1);
  --accent-glow: rgba(240, 77, 38, 0.25);
  --radius: 1.25rem;
  --radius-sm: 0.625rem;
  --sans: "Outfit", system-ui, -apple-system, sans-serif;
  --mono: "JetBrains Mono", "IBM Plex Mono", monospace;
  --ease: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-out: cubic-bezier(0.33, 1, 0.68, 1);
}

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

html {
  scroll-behavior: smooth;
  background: var(--bg);
}

/* ── Scrollbar ── */
* { scrollbar-width: thin; scrollbar-color: #333 transparent; }
*::-webkit-scrollbar { width: 5px; height: 5px; }
*::-webkit-scrollbar-track { background: transparent; }
*::-webkit-scrollbar-thumb { background: #333; border-radius: 3px; }
*::-webkit-scrollbar-thumb:hover { background: #555; }

/* ── Selection ── */
::selection { background: rgba(240, 77, 38, 0.4); color: #fff; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-weight: 400;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ── Grain texture on fixed pseudo-element (perf-safe) ── */
body::after {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 9999;
  opacity: 0.025;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='0.5'/%3E%3C/svg%3E");
}

.container {
  width: min(1080px, calc(100% - 48px));
  margin: 0 auto;
}

/* ═══════════════════════════════════════════
   TOPBAR — Liquid glass refraction
   ═══════════════════════════════════════════ */
.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  border-bottom: 1px solid var(--border-subtle);
  background: rgba(9, 9, 11, 0.72);
  backdrop-filter: blur(20px) saturate(1.4);
  -webkit-backdrop-filter: blur(20px) saturate(1.4);
  box-shadow: inset 0 -1px 0 rgba(255, 255, 255, 0.04);
}

.topbar-inner {
  min-height: 60px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
}

.brand {
  color: var(--text);
  text-decoration: none;
  font-family: var(--sans);
  font-size: 17px;
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1;
  transition: opacity 0.3s var(--ease);
}

.brand:hover { opacity: 0.7; }
.brand span { color: var(--accent); }

.nav {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.nav a {
  color: var(--text-4);
  text-decoration: none;
  font-family: var(--mono);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-size: 11px;
  font-weight: 500;
  transition: color 0.3s var(--ease);
}

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

/* ═══════════════════════════════════════════
   HERO — Asymmetric split (DESIGN_VARIANCE:8)
   Left-aligned content, right status panel
   ═══════════════════════════════════════════ */
.hero {
  padding: 80px 0 56px;
  border-bottom: 1px solid var(--border);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.6fr 0.8fr;
  gap: 48px;
  align-items: end;
}

.eyebrow {
  color: var(--accent);
  font-family: var(--mono);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-size: 11px;
  font-weight: 500;
  margin-bottom: 16px;
  display: inline-flex;
  align-items: center;
  gap: 10px;
}

.eyebrow::before {
  content: "";
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent);
  animation: status-pulse 2.4s ease-in-out infinite;
}

.hero h1 {
  font-family: var(--sans);
  font-size: clamp(38px, 5.5vw, 60px);
  font-weight: 800;
  line-height: 1.0;
  letter-spacing: -0.04em;
  margin-bottom: 20px;
  max-width: 16ch;
  color: var(--text);
}

.hero-lead {
  color: var(--text-3);
  font-size: 17px;
  max-width: 48ch;
  line-height: 1.65;
}

/* Hero aside — status indicators */
.hero-aside {
  display: flex;
  flex-direction: column;
  gap: 1px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.hero-stat {
  background: var(--bg-elevated);
  padding: 18px 20px;
  display: flex;
  align-items: baseline;
  gap: 12px;
}

.hero-stat-number {
  font-family: var(--mono);
  font-size: 28px;
  font-weight: 600;
  letter-spacing: -0.04em;
  color: var(--text);
}

.hero-stat-label {
  font-family: var(--mono);
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-4);
}

/* ═══════════════════════════════════════════
   SECTIONS
   ═══════════════════════════════════════════ */
.section {
  padding: 48px 0 56px;
}

.section-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 24px;
  gap: 16px;
}

.section h2 {
  font-family: var(--sans);
  font-size: clamp(24px, 3.5vw, 34px);
  font-weight: 700;
  line-height: 1.05;
  letter-spacing: -0.035em;
}

.section-count {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--text-4);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  white-space: nowrap;
}

/* ═══════════════════════════════════════════
   FEATURED GRID — Asymmetric 2fr/1fr
   ═══════════════════════════════════════════ */
.featured-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr;
  gap: 12px;
  margin-bottom: 12px;
}

/* ═══════════════════════════════════════════
   POST GRID — 2-column
   ═══════════════════════════════════════════ */
.post-grid {
  display: grid;
  gap: 12px;
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

/* ═══════════════════════════════════════════
   POST CARD
   ═══════════════════════════════════════════ */
.post-card {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 22px;
  text-decoration: none;
  color: inherit;
  background: var(--bg-elevated);
  display: flex;
  flex-direction: column;
  transition: all 0.35s var(--ease);
}

.post-card:hover {
  border-color: var(--accent-glow);
  transform: translateY(-2px);
  box-shadow:
    0 0 0 1px var(--accent-dim),
    0 16px 40px -12px rgba(0, 0, 0, 0.5);
}

.post-card:active {
  transform: translateY(0) scale(0.985);
}

.post-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 10px;
  margin-bottom: 12px;
  color: var(--text-4);
  font-family: var(--mono);
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.post-meta .tag {
  color: var(--accent);
  font-weight: 500;
}

.post-card h3 {
  font-size: 19px;
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin-bottom: 8px;
  color: var(--text);
}

.post-featured h3 {
  font-size: 24px;
  letter-spacing: -0.03em;
}

.post-card p {
  color: var(--text-3);
  font-size: 14px;
  line-height: 1.55;
  margin-top: auto;
}

/* ═══════════════════════════════════════════
   ARCHIVE LIST — divide-y, no card boxes
   ═══════════════════════════════════════════ */
.archive-list {
  border-top: 1px solid var(--border);
}

.archive-item {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 20px;
  align-items: baseline;
  padding: 16px 0;
  border-bottom: 1px solid var(--border);
  text-decoration: none;
  color: inherit;
  transition: all 0.3s var(--ease);
}

.archive-item:hover {
  padding-left: 8px;
}

.archive-item:hover h3 {
  color: var(--accent);
}

.archive-meta {
  color: var(--text-4);
  font-family: var(--mono);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  font-size: 11px;
  white-space: nowrap;
}

.archive-item h3 {
  font-size: 16px;
  font-weight: 500;
  line-height: 1.3;
  color: var(--text-2);
  transition: color 0.3s var(--ease);
}

/* ═══════════════════════════════════════════
   STAGGER ANIMATION — sequential reveal
   ═══════════════════════════════════════════ */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

.stagger > * {
  opacity: 0;
  animation: fadeUp 0.6s var(--ease) forwards;
  animation-delay: calc(var(--i, 0) * 80ms);
}

@keyframes status-pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.35; transform: scale(1.8); }
}

/* ═══════════════════════════════════════════
   ARTICLE PAGES
   ═══════════════════════════════════════════ */
.article {
  padding: 56px 0 72px;
}

.article .meta-row {
  color: var(--text-4);
  font-family: var(--mono);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-size: 11px;
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.article h1 {
  font-family: var(--sans);
  font-size: clamp(30px, 5vw, 50px);
  font-weight: 800;
  line-height: 1.05;
  letter-spacing: -0.04em;
  margin-bottom: 16px;
  max-width: 18ch;
}

.article .dek {
  color: var(--text-3);
  font-size: 18px;
  max-width: 56ch;
  margin-bottom: 32px;
  line-height: 1.6;
}

.content {
  max-width: 720px;
}

.content p {
  margin-bottom: 18px;
  font-size: 17px;
  line-height: 1.75;
  color: var(--text-2);
  max-width: 65ch;
}

.content h2 {
  margin-top: 40px;
  margin-bottom: 14px;
  font-family: var(--sans);
  font-size: 26px;
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.03em;
  color: var(--text);
}

.content ul {
  margin: 12px 0 18px 20px;
}

.content li {
  margin-bottom: 10px;
  font-size: 17px;
  line-height: 1.65;
  color: var(--text-2);
}

.content li::marker {
  color: var(--accent);
}

.content strong {
  font-weight: 600;
  color: var(--text);
}

.content code {
  font-family: var(--mono);
  font-size: 0.88em;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 2px 6px;
}

/* ═══════════════════════════════════════════
   FIGURES & VISUALS
   ═══════════════════════════════════════════ */
.figure {
  margin: 32px 0;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
  background: var(--bg-elevated);
}

.visual {
  min-height: 170px;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
}

.figure figcaption {
  padding: 12px 16px;
  color: var(--text-4);
  font-size: 13px;
  font-family: var(--mono);
  letter-spacing: 0.01em;
}

.visual-code {
  padding: 18px 20px;
  font-family: var(--mono);
  font-size: 13px;
  color: var(--accent);
  white-space: pre-line;
  line-height: 1.75;
}

.visual-bars {
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  align-items: end;
  gap: 8px;
  padding: 20px;
}

.visual-bars i {
  display: block;
  border-radius: 3px 3px 1px 1px;
  background: linear-gradient(180deg, var(--accent), rgba(240, 77, 38, 0.3));
}

.visual-diagram {
  position: relative;
  overflow: hidden;
}

.visual-diagram::before,
.visual-diagram::after {
  content: "";
  position: absolute;
  background: var(--accent);
  opacity: 0.2;
}

.visual-diagram::before {
  left: 8%; right: 8%; top: 50%; height: 1px;
}

.visual-diagram::after {
  top: 8%; bottom: 8%; left: 50%; width: 1px;
}

.visual-gradient {
  background:
    radial-gradient(circle at 24% 30%, rgba(240, 77, 38, 0.2), transparent 40%),
    radial-gradient(circle at 76% 60%, rgba(240, 77, 38, 0.08), transparent 45%),
    var(--bg);
}

.visual-matrix {
  padding: 18px 20px;
  font-family: var(--mono);
  font-size: 13px;
  color: var(--text-3);
  white-space: pre-line;
  line-height: 1.75;
}

/* ═══════════════════════════════════════════
   ARTICLE NAV
   ═══════════════════════════════════════════ */
.article-nav {
  margin-top: 40px;
  border-top: 1px solid var(--border);
  padding-top: 20px;
  display: flex;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}

.article-nav a {
  color: var(--text-4);
  text-decoration: none;
  font-family: var(--mono);
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  transition: color 0.3s var(--ease);
}

.article-nav a:hover { color: var(--accent); }

/* ═══════════════════════════════════════════
   FOOTER
   ═══════════════════════════════════════════ */
.footer {
  border-top: 1px solid var(--border);
  padding: 28px 0 44px;
  color: var(--text-4);
  font-size: 12px;
  font-family: var(--mono);
  letter-spacing: 0.02em;
}

/* ═══════════════════════════════════════════
   RESPONSIVE
   ═══════════════════════════════════════════ */
@media (max-width: 900px) {
  .hero-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .hero-aside {
    flex-direction: row;
  }

  .hero-stat { flex: 1; }

  .featured-grid {
    grid-template-columns: 1fr;
  }

  .post-grid {
    grid-template-columns: 1fr;
  }

  .archive-item {
    grid-template-columns: 1fr;
    gap: 4px;
  }
}

@media (max-width: 640px) {
  .container {
    width: calc(100% - 32px);
  }

  .topbar-inner {
    min-height: 52px;
  }

  .hero { padding: 56px 0 40px; }

  .hero h1 { font-size: clamp(32px, 8vw, 48px); }

  .hero-aside { flex-direction: column; }

  .article .dek { font-size: 16px; }
  .content p { font-size: 16px; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation: none !important;
    transition-duration: 0.01ms !important;
  }
  html { scroll-behavior: auto; }
}