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

:root {
  --bg:        #ffffff;
  --bg-raised: #f8f9fb;
  --bg-card:   #ffffff;
  --border:    #e4e7ed;
  --border-strong: #d0d5de;
  --text:      #1a1f2e;
  --text-muted:#6b7280;
  --accent:    #2563eb;
  --accent-light: #eff6ff;
  --font:      'Inter', system-ui, sans-serif;
  --mono:      'JetBrains Mono', 'Fira Code', monospace;
  --radius:    10px;
  --max-w:     1100px;
}

html { height: 100%; }

body {
  background: var(--bg-raised);
  color: var(--text);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  min-height: 100%;
}

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

/* ─── Buttons ───────────────────────────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 24px;
  border-radius: 8px;
  font-size: .95rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: background .18s, color .18s, border-color .18s, opacity .18s;
}
.btn-primary {
  background: var(--accent);
  color: #fff;
}
.btn-primary:hover { background: #1d4ed8; }

.btn-outline {
  background: transparent;
  color: var(--text);
  border: 1.5px solid var(--border-strong);
}
.btn-outline:hover { border-color: var(--accent); color: var(--accent); }

/* ─── Navbar ────────────────────────────────────────────────────────────── */
.navbar {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 100;
  background: rgba(255,255,255,.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}
.nav-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
  height: 60px;
  display: flex;
  align-items: center;
  gap: 32px;
}
.nav-logo {
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: -.01em;
  white-space: nowrap;
}
.dot { color: var(--accent); }

.nav-links {
  display: flex;
  gap: 28px;
  flex: 1;
}
.nav-links a {
  font-size: .9rem;
  color: var(--text-muted);
  transition: color .15s;
}
.nav-links a:hover,
.nav-links a.active { color: var(--accent); }

.nav-actions {
  margin-left: auto;
  display: flex;
  gap: 10px;
}

/* ─── Hub Layout ────────────────────────────────────────────────────────── */
.hub-layout {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 60px 24px 0;
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 32px;
  min-height: 100vh;
}

/* ─── Sidebar ───────────────────────────────────────────────────────────── */
.hub-sidebar {
  position: sticky;
  top: 76px;
  align-self: start;
  padding: 24px 0;
  display: flex;
  flex-direction: column;
  gap: 24px;
  max-height: calc(100vh - 76px);
  overflow-y: auto;
}

.hub-sidebar-section h3 {
  font-size: .72rem;
  font-family: var(--mono);
  font-weight: 500;
  letter-spacing: .05em;
  color: var(--accent);
  margin-bottom: 10px;
}
.hub-sidebar-section h3::before { content: '# '; opacity: .6; }

/* category nav */
.hub-cat-nav {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.hub-cat-nav li a {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding: 7px 12px;
  border-radius: 8px;
  font-size: .88rem;
  color: var(--text-muted);
  transition: background .15s, color .15s;
}
.hub-cat-nav li a:hover {
  background: var(--bg-card);
  color: var(--text);
}
.hub-cat-nav li a.active {
  background: var(--accent-light);
  color: var(--accent);
  font-weight: 600;
}
.hub-cat-count {
  font-size: .75rem;
  font-family: var(--mono);
  background: var(--bg-raised);
  border-radius: 6px;
  padding: 1px 7px;
  color: var(--text-muted);
  min-width: 22px;
  text-align: center;
}
.hub-cat-nav li a.active .hub-cat-count {
  background: rgba(37,99,235,.12);
  color: var(--accent);
}

/* search */
.hub-search {
  width: 100%;
  padding: 9px 12px;
  border: 1.5px solid var(--border);
  border-radius: 8px;
  font-size: .88rem;
  font-family: var(--font);
  background: var(--bg-card);
  color: var(--text);
  outline: none;
  transition: border-color .15s;
}
.hub-search::placeholder { color: var(--text-muted); }
.hub-search:focus { border-color: var(--accent); }

/* tag cloud */
.hub-tag-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}
.hub-tag-pill {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 20px;
  font-size: .75rem;
  font-weight: 500;
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-muted);
  cursor: pointer;
  transition: background .15s, color .15s, border-color .15s;
}
.hub-tag-pill:hover {
  border-color: var(--accent);
  color: var(--accent);
}
.hub-tag-pill.active {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}
.hub-tag-pill .tag-count {
  font-family: var(--mono);
  font-size: .68rem;
  opacity: .7;
  margin-left: 3px;
}

/* ─── Main Area ─────────────────────────────────────────────────────────── */
.hub-main {
  padding: 24px 0 64px;
  min-width: 0;
}

/* ─── Hero (compact) ────────────────────────────────────────────────────── */
.hub-hero {
  margin-bottom: 28px;
}
.hub-hero h1 {
  font-size: clamp(1.4rem, 2.2vw, 1.7rem);
  font-weight: 700;
  letter-spacing: -.015em;
  margin-bottom: 4px;
}
.hub-hero p {
  color: var(--text-muted);
  font-size: .92rem;
}
.hub-hero .hub-result-count {
  font-family: var(--mono);
  font-size: .78rem;
  color: var(--accent);
  margin-top: 8px;
}

/* ─── Concept Cards ─────────────────────────────────────────────────────── */
.hub-cards {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.hub-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 24px;
  transition: border-color .18s, box-shadow .18s;
}
.hub-card:hover {
  border-color: var(--border-strong);
  box-shadow: 0 2px 12px rgba(0,0,0,.04);
}

.hub-card-header {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  margin-bottom: 8px;
}
.hub-card-icon {
  font-size: 1.3rem;
  line-height: 1;
  flex-shrink: 0;
  margin-top: 2px;
}
.hub-card-title {
  font-size: 1.05rem;
  font-weight: 650;
  letter-spacing: -.01em;
}
.hub-card-category {
  margin-left: auto;
  flex-shrink: 0;
}

.hub-card-desc {
  color: var(--text-muted);
  font-size: .9rem;
  line-height: 1.55;
  margin-bottom: 12px;
}

/* metadata badges */
.hub-meta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 12px;
}

.hub-badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 3px 10px;
  border-radius: 6px;
  font-size: .75rem;
  font-weight: 500;
  background: var(--bg-raised);
  border: 1px solid var(--border);
  color: var(--text-muted);
}
.hub-badge-label {
  opacity: .7;
  font-weight: 400;
}
.hub-badge.badge-accent {
  background: var(--accent-light);
  border-color: rgba(37,99,235,.2);
  color: var(--accent);
}
.hub-badge.badge-green {
  background: #f0fdf4;
  border-color: rgba(22,163,74,.2);
  color: #16a34a;
}
.hub-badge.badge-orange {
  background: #fff7ed;
  border-color: rgba(234,88,12,.2);
  color: #ea580c;
}
.hub-badge.badge-violet {
  background: #f5f3ff;
  border-color: rgba(124,58,237,.2);
  color: #7c3aed;
}

/* tags on cards */
.hub-card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  margin-bottom: 12px;
}
.hub-card-tag {
  display: inline-block;
  padding: 2px 9px;
  border-radius: 20px;
  font-size: .72rem;
  font-weight: 500;
  background: var(--bg-raised);
  color: var(--text-muted);
  cursor: pointer;
  transition: background .12s, color .12s;
}
.hub-card-tag:hover {
  background: var(--accent-light);
  color: var(--accent);
}

/* actions */
.hub-actions {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}
.hub-btn {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 6px 14px;
  border-radius: 7px;
  font-size: .8rem;
  font-weight: 600;
  font-family: var(--font);
  cursor: pointer;
  border: 1.5px solid var(--border);
  background: var(--bg-card);
  color: var(--text-muted);
  transition: border-color .15s, color .15s, background .15s;
}
.hub-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
}
.hub-btn-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}
.hub-btn-primary:hover {
  background: #1d4ed8;
  border-color: #1d4ed8;
}

/* JSON preview */
.hub-json-toggle {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 6px 14px;
  border-radius: 7px;
  font-size: .8rem;
  font-weight: 600;
  font-family: var(--font);
  cursor: pointer;
  border: 1.5px solid var(--border);
  background: var(--bg-card);
  color: var(--text-muted);
  transition: border-color .15s, color .15s;
}
.hub-json-toggle:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.hub-json-preview {
  margin-top: 12px;
  background: var(--bg-raised);
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow: hidden;
  display: none;
}
.hub-json-preview.open {
  display: block;
}
.hub-json-preview pre {
  padding: 16px;
  overflow-x: auto;
  font-family: var(--mono);
  font-size: .78rem;
  line-height: 1.55;
  color: var(--text);
  max-height: 400px;
  overflow-y: auto;
}

/* ─── Empty State ───────────────────────────────────────────────────────── */
.hub-empty {
  text-align: center;
  padding: 64px 24px;
  color: var(--text-muted);
}
.hub-empty-icon {
  font-size: 2.5rem;
  margin-bottom: 12px;
  opacity: .5;
}
.hub-empty h3 {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 4px;
}
.hub-empty p {
  font-size: .9rem;
}

/* ─── Toast ─────────────────────────────────────────────────────────────── */
.hub-toast {
  position: fixed;
  bottom: 28px;
  left: 50%;
  transform: translateX(-50%) translateY(80px);
  background: var(--text);
  color: #fff;
  padding: 10px 22px;
  border-radius: 8px;
  font-size: .88rem;
  font-weight: 500;
  z-index: 200;
  pointer-events: none;
  opacity: 0;
  transition: transform .3s ease, opacity .3s ease;
}
.hub-toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ─── Responsive ────────────────────────────────────────────────────────── */
@media (max-width: 800px) {
  .hub-layout {
    grid-template-columns: 1fr;
    gap: 0;
  }
  .hub-sidebar {
    position: static;
    max-height: none;
    padding: 16px 0 0;
    border-bottom: 1px solid var(--border);
    margin-bottom: 8px;
  }
  .nav-links { display: none; }
  .nav-actions .btn-outline { display: none; }
}