@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&family=JetBrains+Mono:wght@400;500&family=Space+Grotesk:wght@500;600;700&display=swap');

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

:root {
  --c-black: #000000;
  --c-white: #ffffff;
  --c-gray-100: #f5f5f5;
  --c-gray-200: #e8e8e8;
  --c-gray-400: #999999;
  --c-gray-600: #555555;
  --c-accent: #000000;
  --unit: 8px;
  --max-w: 1280px;
  --font-sans: 'Space Grotesk', 'Inter', Helvetica, Arial, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  --radius-card: 10px;
  --header-h: 64px;
}

html { font-size: 16px; scroll-behavior: smooth; }
body {
  font-family: var(--font-sans);
  font-weight: 400;
  line-height: 1.6;
  color: var(--c-black);
  background: var(--c-white);
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }
a:hover { text-decoration: underline; }
img { display: block; max-width: 100%; height: auto; }
ol, ul { list-style: none; }
time { font-size: 0.8125rem; color: var(--c-gray-600); font-family: var(--font-mono); }

/* ── PAGE WRAPPER ── */
.page-wrapper { display: flex; flex-direction: column; min-height: 100vh; }

/* ── HEADER ── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--c-black);
  color: var(--c-white);
  height: var(--header-h);
  border-bottom: 1px solid #222;
}
.header-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  height: 100%;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  padding: 0 calc(var(--unit) * 3);
  gap: calc(var(--unit) * 2);
}
.header-nav-left { display: flex; align-items: center; justify-content: flex-start; overflow: hidden; }
.header-nav-right { display: flex; align-items: center; justify-content: flex-end; }
.header-brand { display: flex; justify-content: center; flex-shrink: 0; }
.brand-link { display: flex; align-items: center; gap: var(--unit); color: var(--c-white); }
.brand-link:hover { text-decoration: none; opacity: 0.8; }
.site-brand-text { font-size: 1rem; font-weight: 700; letter-spacing: -0.02em; white-space: nowrap; }
.site-logo { height: 32px; width: auto; }
.header-tag {
  font-size: 0.6875rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  background: var(--c-white);
  color: var(--c-black);
  padding: 2px 8px;
  border-radius: 4px;
}

/* MAIN NAV */
.main-nav ol {
  display: flex;
  gap: 0;
  align-items: center;
  flex-wrap: nowrap;
  overflow: hidden;
}
.main-nav ol li { flex-shrink: 0; }
.main-nav ol li a {
  display: block;
  color: var(--c-white);
  font-size: 0.8125rem;
  font-weight: 500;
  padding: 0 calc(var(--unit) * 1.5);
  height: var(--header-h);
  line-height: var(--header-h);
  white-space: nowrap;
  border-right: 1px solid #222;
  transition: background 0.15s;
}
.main-nav ol li:first-child a { border-left: 1px solid #222; }
.main-nav ol li a:hover { background: #1a1a1a; text-decoration: none; }

/* ── HERO ── */
.hero-section {
  background: var(--c-black);
  color: var(--c-white);
  min-height: 45vh;
  display: flex;
  align-items: flex-end;
  padding: calc(var(--unit) * 6) 0 calc(var(--unit) * 5);
  position: relative;
  overflow: hidden;
}
.hero-section::after {
  content: '';
  position: absolute;
  inset: 0;
  background: repeating-linear-gradient(
    0deg,
    transparent,
    transparent 39px,
    rgba(255,255,255,0.04) 39px,
    rgba(255,255,255,0.04) 40px
  );
  pointer-events: none;
}
.hero-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 calc(var(--unit) * 3);
  width: 100%;
  position: relative;
  z-index: 1;
}
.hero-text { max-width: 680px; }
.hero-badges { display: flex; gap: var(--unit); flex-wrap: wrap; margin-bottom: calc(var(--unit) * 2); }
.badge {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  border: 1px solid rgba(255,255,255,0.4);
  padding: 3px 10px;
  border-radius: 20px;
}
.hero-section h1 {
  font-size: clamp(1.75rem, 4vw, 3rem);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.03em;
  margin-bottom: calc(var(--unit) * 2);
}
.hero-desc { font-size: 1rem; line-height: 1.65; opacity: 0.8; max-width: 560px; }

/* ── PAGE HERO (non-home) ── */
.page-hero {
  background: var(--c-black);
  color: var(--c-white);
  padding: calc(var(--unit) * 6) 0 calc(var(--unit) * 5);
}
.page-hero-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 calc(var(--unit) * 3);
}
.page-hero h1 {
  font-size: clamp(1.5rem, 3.5vw, 2.5rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin: calc(var(--unit) * 1.5) 0 calc(var(--unit) * 2);
}
.page-hero-desc { font-size: 1rem; opacity: 0.78; max-width: 520px; }

/* article header */
.article-header-section {
  background: var(--c-black);
  color: var(--c-white);
  padding: calc(var(--unit) * 6) 0 calc(var(--unit) * 5);
}
.article-header-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 calc(var(--unit) * 3);
  max-width: 860px;
}
.article-header-inner h1 {
  font-size: clamp(1.5rem, 3.5vw, 2.25rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.2;
  margin: calc(var(--unit) * 1.5) 0 var(--unit);
}
.article-meta { display: flex; gap: calc(var(--unit) * 2); flex-wrap: wrap; margin-bottom: calc(var(--unit) * 1.5); }
.article-date { font-family: var(--font-mono); font-size: 0.8125rem; color: rgba(255,255,255,0.6); }
.article-lead { font-size: 1rem; opacity: 0.78; max-width: 560px; }

/* ── BREADCRUMB ── */
.breadcrumb { font-size: 0.8125rem; color: rgba(255,255,255,0.55); display: flex; align-items: center; gap: 4px; flex-wrap: wrap; }
.breadcrumb a { color: rgba(255,255,255,0.7); }
.breadcrumb a:hover { color: var(--c-white); text-decoration: none; }
.breadcrumb-sep { margin: 0 2px; }

/* ── CONTENT SECTION ── */
.content-section { flex: 1; padding: calc(var(--unit) * 5) 0; background: var(--c-white); }
.section-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 calc(var(--unit) * 3);
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: calc(var(--unit) * 5);
  align-items: start;
}

/* ── ASIDE / SIDEBAR ── */
.sidebar { position: sticky; top: calc(var(--header-h) + 24px); }
.sidebar-block {
  border-top: 2px solid var(--c-black);
  padding: calc(var(--unit) * 2) 0 calc(var(--unit) * 3);
  margin-bottom: calc(var(--unit) * 3);
}
.sidebar-block h3 {
  font-size: 0.6875rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: calc(var(--unit) * 1.5);
}
.sidebar-block h3 > span { display: inline; }
.sidebar-nav { display: flex; flex-direction: column; gap: 4px; }
.sidebar-nav li a {
  display: block;
  font-size: 0.875rem;
  padding: 6px 0;
  border-bottom: 1px solid var(--c-gray-200);
  color: var(--c-black);
  transition: padding-left 0.15s;
}
.sidebar-nav li a:hover { padding-left: 6px; text-decoration: none; }
.sidebar-note { font-size: 0.875rem; line-height: 1.55; color: var(--c-gray-600); }
.sidebar-count { font-size: 2rem; font-weight: 700; line-height: 1; font-family: var(--font-mono); }

.info-list { font-size: 0.875rem; display: grid; grid-template-columns: auto 1fr; gap: 4px 12px; }
.info-list dt { font-weight: 600; color: var(--c-gray-600); }
.info-list dd { color: var(--c-black); }

/* ── MAIN CONTENT ── */
.main-content { min-width: 0; }

/* ── CONTENT BODY ── */
.content-body {
  font-size: 1rem;
  line-height: 1.75;
  color: var(--c-black);
  margin-bottom: calc(var(--unit) * 5);
}
.content-body h2 { font-size: 1.375rem; font-weight: 700; margin: calc(var(--unit) * 4) 0 calc(var(--unit) * 1.5); letter-spacing: -0.02em; border-left: 4px solid var(--c-black); padding-left: 12px; }
.content-body h3 { font-size: 1.125rem; font-weight: 600; margin: calc(var(--unit) * 3) 0 var(--unit); }
.content-body p { margin-bottom: calc(var(--unit) * 2); }
.content-body ul, .content-body ol { margin: calc(var(--unit) * 2) 0 calc(var(--unit) * 2) calc(var(--unit) * 3); }
.content-body ul { list-style: disc; }
.content-body ol { list-style: decimal; }
.content-body li { margin-bottom: 6px; }
.content-body a { color: var(--c-black); text-decoration: underline; text-underline-offset: 3px; }
.content-body a:hover { opacity: 0.6; }
.content-body strong { font-weight: 700; }
.content-body code { font-family: var(--font-mono); font-size: 0.875em; background: var(--c-gray-100); padding: 2px 6px; border-radius: 3px; }
.content-body blockquote { border-left: 3px solid var(--c-black); padding-left: calc(var(--unit) * 2); color: var(--c-gray-600); margin: calc(var(--unit) * 3) 0; }
.content-body table { width: 100%; border-collapse: collapse; margin: calc(var(--unit) * 3) 0; font-size: 0.9375rem; }
.content-body th, .content-body td { border: 1px solid var(--c-gray-200); padding: 8px 12px; text-align: left; }
.content-body th { background: var(--c-black); color: var(--c-white); font-weight: 600; }

/* ── BLOCK HEADING ── */
.block-heading { margin-bottom: calc(var(--unit) * 3); border-top: 2px solid var(--c-black); padding-top: calc(var(--unit) * 2); }
.block-heading h2 { font-size: 1.125rem; font-weight: 700; letter-spacing: 0.04em; text-transform: uppercase; }
.block-heading h2 > span { display: inline; }

/* ── CARDS GRID ── */
.cards-grid {
  display: grid;
  gap: calc(var(--unit) * 2);
  margin-bottom: calc(var(--unit) * 5);
}
.cards-grid--topic { grid-template-columns: repeat(2, 1fr); }
.cards-grid--articles { grid-template-columns: repeat(2, 1fr); }

.card {
  display: flex;
  flex-direction: column;
  gap: var(--unit);
  padding: calc(var(--unit) * 3);
  border-radius: var(--radius-card);
  background: var(--c-gray-100);
  transition: transform 0.18s, background 0.18s;
  cursor: pointer;
}
.card:hover { background: var(--c-black); color: var(--c-white); transform: translateY(-2px); text-decoration: none; }
.card:hover time { color: rgba(255,255,255,0.6); }
.card > strong { font-size: 1rem; font-weight: 700; line-height: 1.3; display: block; }
.card__desc { font-size: 0.875rem; line-height: 1.55; color: var(--c-gray-600); }
.card:hover .card__desc { color: rgba(255,255,255,0.7); }
.card__meta { font-size: 0.8125rem; font-family: var(--font-mono); color: var(--c-gray-400); }
.card--topic > strong { font-size: 1.0625rem; font-weight: 700; }

/* ── CHILD CARDS (topic page) ── */
.child-cards { display: flex; flex-direction: column; gap: calc(var(--unit) * 1.5); margin-bottom: calc(var(--unit) * 5); }
.child-card {
  display: grid;
  grid-template-columns: 1fr auto;
  grid-template-rows: auto auto;
  align-items: start;
  padding: calc(var(--unit) * 2.5) calc(var(--unit) * 3);
  background: var(--c-gray-100);
  border-radius: var(--radius-card);
  border-left: 3px solid var(--c-black);
  transition: background 0.15s, border-color 0.15s;
  gap: 4px calc(var(--unit) * 2);
}
.child-card:hover { background: var(--c-black); color: var(--c-white); text-decoration: none; border-left-color: var(--c-white); }
.child-card > strong { font-size: 1rem; font-weight: 700; grid-column: 1; grid-row: 1; }
.child-card__meta { grid-column: 2; grid-row: 1; align-self: center; }
.child-card__desc { font-size: 0.875rem; color: var(--c-gray-600); grid-column: 1 / -1; grid-row: 2; }
.child-card:hover .child-card__desc { color: rgba(255,255,255,0.7); }
.child-card:hover .child-card__meta time { color: rgba(255,255,255,0.5); }

/* ── ABOUT NAV GRID ── */
.about-nav-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: calc(var(--unit) * 2);
  margin-bottom: calc(var(--unit) * 5);
}
.about-nav-card {
  display: flex;
  flex-direction: column;
  gap: var(--unit);
  padding: calc(var(--unit) * 3);
  background: var(--c-gray-100);
  border-radius: var(--radius-card);
  border-top: 3px solid var(--c-black);
  transition: background 0.15s;
}
.about-nav-card:hover { background: var(--c-black); color: var(--c-white); text-decoration: none; }
.about-nav-card > strong { font-size: 1rem; font-weight: 700; display: block; }
.about-nav-card > span { font-size: 0.875rem; color: var(--c-gray-600); line-height: 1.5; }
.about-nav-card:hover > span { color: rgba(255,255,255,0.7); }

/* ── TAG PAGE ── */
.tag-cloud { display: flex; flex-wrap: wrap; gap: var(--unit); }
.tag-pill {
  display: inline-block;
  font-size: 0.8125rem;
  font-weight: 600;
  padding: 6px 14px;
  border: 1.5px solid var(--c-black);
  border-radius: 20px;
  transition: background 0.15s, color 0.15s;
}
.tag-pill:hover, .tag-pill--active { background: var(--c-black); color: var(--c-white); text-decoration: none; }
.tag-items-list { display: flex; flex-direction: column; gap: calc(var(--unit) * 1.5); margin-bottom: calc(var(--unit) * 5); }
.tag-item-link {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: calc(var(--unit) * 2) calc(var(--unit) * 3);
  background: var(--c-gray-100);
  border-radius: var(--radius-card);
  transition: background 0.15s;
}
.tag-item-link:hover { background: var(--c-black); color: var(--c-white); text-decoration: none; }
.tag-item-link > strong { font-size: 0.9375rem; font-weight: 600; }
.tag-item-meta { font-size: 0.8125rem; font-family: var(--font-mono); color: var(--c-gray-400); }
.tag-item-link:hover .tag-item-meta { color: rgba(255,255,255,0.5); }

/* ── FOOTER ── */
.site-footer {
  background: var(--c-black);
  color: var(--c-white);
  border-top: 1px solid #222;
  padding: calc(var(--unit) * 3) 0;
  margin-top: auto;
}
.footer-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 calc(var(--unit) * 3);
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: calc(var(--unit) * 3);
}
.footer-brand a { font-size: 0.9375rem; font-weight: 700; color: var(--c-white); }
.footer-brand a:hover { opacity: 0.7; text-decoration: none; }
.footer-nav { display: flex; gap: calc(var(--unit) * 3); justify-content: center; }
.footer-nav a { font-size: 0.875rem; color: rgba(255,255,255,0.65); padding: 8px 0; min-height: 40px; display: flex; align-items: center; }
.footer-nav a:hover { color: var(--c-white); text-decoration: none; }
.footer-copy { text-align: right; font-size: 0.8125rem; color: rgba(255,255,255,0.45); font-family: var(--font-mono); }

/* ── ANIMATIONS ── */
@media (prefers-reduced-motion: no-preference) {
  .card, .child-card, .about-nav-card, .tag-item-link, .tag-pill {
    will-change: transform;
  }
  .card:hover { transform: translateY(-2px); }
  .child-card:hover { transform: translateX(3px); }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; animation: none !important; }
}

/* ── RESPONSIVE ── */
@media (max-width: 1024px) {
  .section-inner { grid-template-columns: 180px 1fr; gap: calc(var(--unit) * 3); }
  .cards-grid--topic { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  :root { --header-h: 56px; }
  .header-inner { grid-template-columns: 1fr auto; }
  .header-nav-left { display: none; }
  .header-nav-right { display: none; }
  .section-inner { grid-template-columns: 1fr; }
  .sidebar { position: static; display: grid; grid-template-columns: repeat(2, 1fr); gap: calc(var(--unit) * 2); }
  .sidebar-block { margin-bottom: 0; }
  .cards-grid--topic { grid-template-columns: 1fr; }
  .cards-grid--articles { grid-template-columns: 1fr; }
  .about-nav-grid { grid-template-columns: 1fr; }
  .footer-inner { grid-template-columns: 1fr; gap: var(--unit); text-align: center; }
  .footer-copy { text-align: center; }
  .footer-nav { justify-content: center; }
  .hero-section { min-height: 55vw; }
  .child-card { grid-template-columns: 1fr; }
  .child-card__meta { grid-column: 1; grid-row: 2; }
  .child-card__desc { grid-row: 3; }
}

@media (max-width: 480px) {
  .header-inner { padding: 0 calc(var(--unit) * 2); }
  .hero-inner, .page-hero-inner, .article-header-inner, .section-inner, .footer-inner { padding-left: calc(var(--unit) * 2); padding-right: calc(var(--unit) * 2); }
  .block-heading h2 { font-size: 1rem; }
  .sidebar { grid-template-columns: 1fr; }
  .tag-item-link { flex-direction: column; align-items: flex-start; gap: 4px; }
  .main-nav ol li a { padding: 0 calc(var(--unit) * 1); font-size: 0.75rem; }
}