/* ── Reset & Base ─────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg:         #faf9f7;
  --bg-alt:     #f3f1ee;
  --surface:    #ffffff;
  --border:     #e5e2dd;
  --border-mid: #d4d0ca;
  --text:       #1a1917;
  --text-body:  #3d3a35;
  --muted:      #888580;
  --faint:      #b8b5af;

  --accent:     #d4500a;
  --accent-bg:  #fdf1ec;

  --tag-embedded-c:    #1a6b3c;
  --tag-embedded-c-bg: #edf7f1;
  --tag-stm32:         #1a4f8a;
  --tag-stm32-bg:      #eef3fb;
  --tag-ai:            #6b2fa0;
  --tag-ai-bg:         #f5eefb;
  --tag-default:       #7a4a1e;
  --tag-default-bg:    #fdf3ea;

  --font-display: 'Playfair Display', Georgia, serif;
  --font-body:    'Lora', Georgia, serif;
  --font-ui:      'DM Sans', system-ui, sans-serif;
  --font-mono:    'JetBrains Mono', 'Fira Code', monospace;

  --max-w: 1080px;
  --radius: 6px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.08), 0 2px 4px rgba(0,0,0,0.04);
  --transition: 0.16s ease;
}

html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--text-body);
  font-family: var(--font-ui);
  font-size: 15px;
  line-height: 1.65;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }

/* ── Header ──────────────────────────────────────── */
header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(250, 249, 247, 0.93);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 2.5rem;
  height: 58px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
}

.logo {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.2rem;
  color: var(--text);
  letter-spacing: -0.01em;
}
.logo .accent { color: var(--accent); }

nav {
  display: flex;
  align-items: center;
  gap: 0.125rem;
  flex-wrap: wrap;
}

.nav-link {
  font-family: var(--font-ui);
  font-size: 0.78rem;
  font-weight: 500;
  padding: 5px 13px;
  border-radius: 99px;
  color: var(--muted);
  cursor: pointer;
  transition: all var(--transition);
  letter-spacing: 0.01em;
  border: 1px solid transparent;
}
.nav-link:hover   { color: var(--text); background: var(--bg-alt); }
.nav-link.active  { color: #fff; background: var(--text); border-color: var(--text); }

.nav-link.tag-embedded-c.active { background: var(--tag-embedded-c); border-color: var(--tag-embedded-c); }
.nav-link.tag-stm32.active      { background: var(--tag-stm32);      border-color: var(--tag-stm32); }
.nav-link.tag-ai.active         { background: var(--tag-ai);          border-color: var(--tag-ai); }
.nav-link.tag-default.active    { background: var(--tag-default);     border-color: var(--tag-default); }

/* ── Hero ────────────────────────────────────────── */
.hero {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 5rem 2.5rem 4.5rem;
  border-bottom: 1px solid var(--border);
}

.hero-eyebrow {
  font-family: var(--font-ui);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 1.25rem;
}

.hero-title {
  font-family: var(--font-display);
  font-size: clamp(2.4rem, 5vw, 4rem);
  font-weight: 700;
  line-height: 1.12;
  letter-spacing: -0.02em;
  color: var(--text);
  margin-bottom: 1.25rem;
}
.hero-title em { font-style: italic; color: var(--accent); }

.hero-sub {
  font-family: var(--font-body);
  font-size: 1.05rem;
  color: var(--muted);
  max-width: 500px;
  line-height: 1.75;
}

/* ── Posts Section ───────────────────────────────── */
.posts-section {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 3.5rem 2.5rem 7rem;
}

.tag-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 2.25rem;
}
.tag-header.hidden { display: none; }

#active-tag-label {
  font-family: var(--font-display);
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.01em;
}

#clear-tag {
  background: none;
  border: 1px solid var(--border-mid);
  color: var(--muted);
  font-family: var(--font-ui);
  font-size: 0.72rem;
  font-weight: 500;
  padding: 4px 12px;
  border-radius: 99px;
  cursor: pointer;
  transition: all var(--transition);
}
#clear-tag:hover { color: var(--text); border-color: var(--text); background: var(--bg-alt); }

/* ── Posts Grid ──────────────────────────────────── */
.posts-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.5rem;
}

.post-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.75rem 1.875rem;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  cursor: pointer;
  transition: all var(--transition);
  box-shadow: var(--shadow-sm);
}
.post-card:hover {
  border-color: var(--border-mid);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.post-card-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.25rem;
}

.post-tag-badge {
  font-family: var(--font-ui);
  font-size: 0.63rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding: 2px 9px;
  border-radius: 3px;
}
.tag-embedded-c { color: var(--tag-embedded-c); background: var(--tag-embedded-c-bg); }
.tag-stm32      { color: var(--tag-stm32);      background: var(--tag-stm32-bg); }
.tag-ai         { color: var(--tag-ai);          background: var(--tag-ai-bg); }
.tag-default    { color: var(--tag-default);     background: var(--tag-default-bg); }

.post-title {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 700;
  line-height: 1.35;
  color: var(--text);
  letter-spacing: -0.01em;
}

.post-desc {
  font-family: var(--font-body);
  font-size: 0.875rem;
  color: var(--muted);
  line-height: 1.65;
  flex: 1;
}

.post-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 0.5rem;
  padding-top: 0.875rem;
  border-top: 1px solid var(--border);
}

.post-date {
  font-family: var(--font-ui);
  font-size: 0.7rem;
  color: var(--faint);
}

.post-arrow {
  font-size: 0.8rem;
  color: var(--faint);
  transition: all var(--transition);
}
.post-card:hover .post-arrow { color: var(--accent); transform: translateX(3px); }

/* ── Empty State ─────────────────────────────────── */
.empty-state {
  padding: 5rem 2rem;
  text-align: center;
  color: var(--muted);
  font-family: var(--font-body);
  font-size: 0.95rem;
  grid-column: 1 / -1;
}
.empty-state.hidden { display: none; }

/* ── Footer ──────────────────────────────────────── */
footer {
  border-top: 1px solid var(--border);
  padding: 1.75rem 2.5rem;
  text-align: center;
  font-family: var(--font-ui);
  font-size: 0.72rem;
  color: var(--faint);
}
footer a { color: var(--muted); transition: color var(--transition); }
footer a:hover { color: var(--text); }

/* ── Animations ──────────────────────────────────── */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(12px); }
  to   { opacity: 1; transform: translateY(0); }
}
.post-card { animation: fadeUp 0.35s ease both; }

/* ── Responsive ──────────────────────────────────── */
@media (max-width: 640px) {
  .header-inner  { padding: 0 1.25rem; }
  .hero          { padding: 3rem 1.25rem 3rem; }
  .posts-section { padding: 2rem 1.25rem 5rem; }
  .posts-grid    { grid-template-columns: 1fr; gap: 1rem; }
}