:root {
  --bg: #ffffff;
  --text: #0f172a;
  --muted: #64748b;
  --accent: #2563eb;
  --border: #e2e8f0;
  --nav-h: 60px;
}

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

body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* ── Navigation ── */
nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 2rem;
  z-index: 100;
  transition: background 0.3s, border-color 0.3s;
  border-bottom: 1px solid transparent;
}

nav.dark {
  background: rgba(0, 0, 0, 0.45);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom-color: rgba(255, 255, 255, 0.08);
}

nav.light {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom-color: var(--border);
}

nav.dark .nav-brand { color: #fff; }
nav.dark .nav-links a { color: rgba(255, 255, 255, 0.65); }
nav.dark .nav-links a:hover,
nav.dark .nav-links a.active { color: #fff; }

nav.light .nav-brand { color: var(--text); }
nav.light .nav-links a { color: var(--muted); }
nav.light .nav-links a:hover,
nav.light .nav-links a.active { color: var(--accent); }

.nav-brand {
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  letter-spacing: -0.01em;
}

.nav-links {
  display: flex;
  gap: 1.75rem;
  list-style: none;
}

.nav-links a {
  text-decoration: none;
  font-size: 0.875rem;
  font-weight: 500;
  transition: color 0.2s;
}

/* ── Layout ── */
.container {
  max-width: 760px;
  margin: 0 auto;
  padding: 0 2rem;
}

.page-section {
  padding: 5rem 0 4rem;
}

/* ── Typography ── */
.eyebrow {
  display: block;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.6rem;
}

h1 {
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: 1rem;
}

h2 {
  font-size: 1.3rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  line-height: 1.3;
  margin-bottom: 0.4rem;
}

p { color: var(--muted); font-size: 0.975rem; line-height: 1.7; }

/* ── Tags ── */
.tag {
  display: inline-block;
  background: #eff6ff;
  color: #2563eb;
  border-radius: 99px;
  padding: 0.18rem 0.6rem;
  font-size: 0.7rem;
  font-weight: 500;
  margin: 0.2rem 0.2rem 0 0;
}

/* ── Cards ── */
.card {
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.75rem;
  margin-bottom: 1.5rem;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.card:hover {
  border-color: #93c5fd;
  box-shadow: 0 4px 24px rgba(37, 99, 235, 0.07);
}

.card-meta {
  font-size: 0.78rem;
  color: var(--muted);
  margin-top: 0.3rem;
}

.card-desc { margin-top: 0.75rem; }

.card-link {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  color: var(--accent);
  text-decoration: none;
  font-size: 0.83rem;
  font-weight: 500;
  margin-top: 1rem;
}

.card-link:hover { text-decoration: underline; }

/* ── Page header (non-home pages) ── */
.page-header {
  padding-top: calc(var(--nav-h) + 4rem);
  padding-bottom: 2.5rem;
  border-bottom: 1px solid var(--border);
}

.page-header p { margin-top: 0.5rem; }

/* ── Footer ── */
footer {
  border-top: 1px solid var(--border);
  padding: 2rem;
  text-align: center;
}

footer a {
  color: var(--muted);
  text-decoration: none;
  margin: 0 0.6rem;
  font-size: 0.875rem;
  font-weight: 500;
  transition: color 0.2s;
}

footer a:hover { color: var(--accent); }

.footer-copy {
  display: block;
  font-size: 0.76rem;
  color: #94a3b8;
  margin-top: 0.65rem;
}

/* ── Responsive ── */
@media (max-width: 600px) {
  nav { padding: 0 1rem; }
  .nav-links { gap: 1rem; }
  .container { padding: 0 1.25rem; }
  .page-header { padding-top: calc(var(--nav-h) + 2.5rem); }
}