:root {
  --bg: #faf9f5;
  --bg-grad-1: #f5f1e8;
  --bg-grad-2: #faf6ee;
  --surface: #ffffff;
  --surface-2: #f3f1ea;
  --border: rgba(0, 0, 0, 0.08);
  --border-strong: rgba(0, 0, 0, 0.18);
  --text: #1a1a17;
  --text-muted: #6b6a64;
  --text-soft: #8c8b85;
  --accent: #c96442;
  --accent-2: #e8845f;
  --accent-soft: #faece7;
  --success: #1d9e75;
  --success-soft: #e1f5ee;
  --warning: #ba7517;
  --warning-soft: #faeeda;
  --danger: #d85a30;
  --danger-soft: #faece7;
  --info: #378add;
  --info-soft: #e6f1fb;
  --purple: #7f77dd;
  --purple-soft: #eeedfe;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.04), 0 1px 3px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.04), 0 10px 20px rgba(0,0,0,0.04);
  --shadow-lg: 0 10px 25px rgba(0,0,0,0.06), 0 20px 40px rgba(0,0,0,0.05);
  --shadow-glow: 0 0 0 4px rgba(201, 100, 66, 0.12);
  --radius: 10px;
  --radius-lg: 14px;
  --sidebar-w: 268px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Inter, system-ui, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  --ease: cubic-bezier(0.4, 0, 0.2, 1);
  --ease-bounce: cubic-bezier(0.34, 1.56, 0.64, 1);
}

[data-theme="dark"] {
  --bg: #1a1917;
  --bg-grad-1: #1f1e1b;
  --bg-grad-2: #232220;
  --surface: #28272430;
  --surface-2: #34322f;
  --border: rgba(255, 255, 255, 0.08);
  --border-strong: rgba(255, 255, 255, 0.18);
  --text: #f0eee7;
  --text-muted: #b0aea7;
  --text-soft: #8a8881;
  --accent: #e8a08a;
  --accent-2: #f4b89e;
  --accent-soft: rgba(232, 160, 138, 0.15);
  --success: #5dcaa5;
  --success-soft: rgba(93, 202, 165, 0.15);
  --warning: #ef9f27;
  --warning-soft: rgba(239, 159, 39, 0.15);
  --danger: #f0997b;
  --danger-soft: rgba(240, 153, 123, 0.15);
  --info: #85b7eb;
  --info-soft: rgba(133, 183, 235, 0.15);
  --purple: #afa9ec;
  --purple-soft: rgba(175, 169, 236, 0.15);
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.2);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.25), 0 10px 20px rgba(0,0,0,0.2);
  --shadow-lg: 0 10px 25px rgba(0,0,0,0.3), 0 20px 40px rgba(0,0,0,0.25);
  --shadow-glow: 0 0 0 4px rgba(232, 160, 138, 0.18);
}

[data-theme="dark"] .card { background: #2a2926; }
[data-theme="dark"] body::before {
  background:
    radial-gradient(circle at 0% 0%, rgba(232, 160, 138, 0.06), transparent 50%),
    radial-gradient(circle at 100% 100%, rgba(133, 183, 235, 0.05), transparent 50%);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

body {
  display: grid;
  grid-template-columns: var(--sidebar-w) 1fr;
  min-height: 100vh;
  position: relative;
  overflow-x: hidden;
}

body::before {
  content: '';
  position: fixed;
  inset: 0;
  pointer-events: none;
  background:
    radial-gradient(circle at 0% 0%, rgba(201, 100, 66, 0.05), transparent 50%),
    radial-gradient(circle at 100% 100%, rgba(127, 119, 221, 0.04), transparent 50%);
  z-index: 0;
  animation: bgshift 24s ease-in-out infinite alternate;
}

@keyframes bgshift {
  0%   { transform: translate(0, 0) scale(1); }
  100% { transform: translate(2%, -1%) scale(1.05); }
}

/* ========== SIDEBAR ========== */
.sidebar {
  position: sticky;
  top: 0;
  height: 100vh;
  padding: 28px 20px;
  border-right: 1px solid var(--border);
  background: linear-gradient(180deg, var(--bg-grad-1), var(--bg-grad-2));
  display: flex;
  flex-direction: column;
  gap: 22px;
  overflow-y: auto;
  z-index: 10;
  backdrop-filter: blur(8px);
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  animation: fadeInDown 0.6s var(--ease) both;
}

.brand-mark {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 13px;
  letter-spacing: 0.5px;
  box-shadow: 0 4px 12px rgba(201, 100, 66, 0.25);
  animation: float 4s ease-in-out infinite;
  position: relative;
}

.brand-mark::after {
  content: '';
  position: absolute;
  inset: -3px;
  border-radius: 12px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  opacity: 0.3;
  filter: blur(8px);
  z-index: -1;
  animation: glowPulse 3s ease-in-out infinite;
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50%      { transform: translateY(-3px); }
}

@keyframes glowPulse {
  0%, 100% { opacity: 0.25; }
  50%      { opacity: 0.5; }
}

.brand-title {
  font-size: 15px;
  font-weight: 600;
  line-height: 1.2;
}

.brand-sub {
  font-size: 12px;
  color: var(--text-muted);
}

.progress-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 12px 14px;
  animation: fadeInDown 0.6s var(--ease) 0.1s both;
  box-shadow: var(--shadow-sm);
}

.progress-label {
  display: flex;
  justify-content: space-between;
  font-size: 12px;
  color: var(--text-muted);
  margin-bottom: 8px;
}

#progress-count {
  font-weight: 600;
  color: var(--text);
  font-variant-numeric: tabular-nums;
}

.progress-bar {
  height: 6px;
  background: var(--surface-2);
  border-radius: 3px;
  overflow: hidden;
  position: relative;
}

.progress-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--success), #2bc28d);
  transition: width 0.6s var(--ease-bounce);
  position: relative;
  overflow: hidden;
}

.progress-fill::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.4), transparent);
  animation: shimmer 2s linear infinite;
}

@keyframes shimmer {
  0%   { transform: translateX(-100%); }
  100% { transform: translateX(100%); }
}

.toc {
  display: flex;
  flex-direction: column;
  gap: 2px;
  flex: 1;
}

.toc a {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 12px;
  border-radius: 8px;
  color: var(--text);
  text-decoration: none;
  font-size: 14px;
  transition: all 0.2s var(--ease);
  position: relative;
  opacity: 0;
  animation: fadeInLeft 0.4s var(--ease) forwards;
}

.toc a:nth-child(1) { animation-delay: 0.15s; }
.toc a:nth-child(2) { animation-delay: 0.2s; }
.toc a:nth-child(3) { animation-delay: 0.25s; }
.toc a:nth-child(4) { animation-delay: 0.3s; }
.toc a:nth-child(5) { animation-delay: 0.35s; }
.toc a:nth-child(6) { animation-delay: 0.4s; }
.toc a:nth-child(7) { animation-delay: 0.45s; }
.toc a:nth-child(8) { animation-delay: 0.5s; }

.toc a:hover {
  background: var(--surface);
  transform: translateX(2px);
}

.toc a.active {
  background: var(--surface);
  font-weight: 500;
  box-shadow: var(--shadow-sm);
}

.toc a.active::before {
  content: '';
  position: absolute;
  left: -20px;
  top: 50%;
  transform: translateY(-50%);
  width: 3px;
  height: 18px;
  background: var(--accent);
  border-radius: 0 3px 3px 0;
  animation: slideInLeft 0.3s var(--ease);
}

.toc a.done .toc-num {
  background: var(--success);
  color: white;
  border-color: var(--success);
  animation: pop 0.4s var(--ease-bounce);
}

@keyframes pop {
  0%   { transform: scale(0.7); }
  60%  { transform: scale(1.15); }
  100% { transform: scale(1); }
}

.toc-num {
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: var(--surface);
  border: 1px solid var(--border);
  font-size: 11px;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
  transition: all 0.2s var(--ease);
}

.toc a.active .toc-num {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-soft);
}

.sidebar-foot {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding-top: 12px;
  border-top: 1px solid var(--border);
}

.link-btn {
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 12px;
  text-align: left;
  cursor: pointer;
  padding: 6px 8px;
  border-radius: 6px;
  font-family: inherit;
  transition: all 0.15s var(--ease);
}

.link-btn:hover {
  background: var(--surface);
  color: var(--text);
  transform: translateX(2px);
}

/* ========== MAIN ========== */
.main {
  padding: 48px 56px;
  max-width: 880px;
  width: 100%;
  position: relative;
  z-index: 1;
}

.lesson {
  margin-bottom: 80px;
  scroll-margin-top: 24px;
}

.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.7s var(--ease), transform 0.7s var(--ease);
}

.reveal.in {
  opacity: 1;
  transform: translateY(0);
}

.lesson-head {
  margin-bottom: 28px;
}

.lesson-tag {
  display: inline-block;
  font-size: 11px;
  font-weight: 600;
  color: var(--accent);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 8px;
  padding: 4px 10px;
  background: var(--accent-soft);
  border-radius: 999px;
  position: relative;
  overflow: hidden;
}

.lesson-tag::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.6), transparent);
  transform: translateX(-100%);
  animation: tagShimmer 3.5s ease-in-out infinite;
}

@keyframes tagShimmer {
  0%, 60%, 100% { transform: translateX(-100%); }
  80%           { transform: translateX(100%); }
}

h1 {
  font-size: 34px;
  font-weight: 700;
  margin: 0 0 12px;
  letter-spacing: -0.02em;
  background: linear-gradient(135deg, var(--text), var(--text-muted));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  line-height: 1.15;
}

h3 {
  font-size: 17px;
  font-weight: 600;
  margin: 0 0 12px;
}

.lede {
  font-size: 16px;
  color: var(--text-muted);
  margin: 0;
  max-width: 600px;
  line-height: 1.6;
}

.muted {
  color: var(--text-muted);
  font-size: 14px;
}

p { margin: 0 0 12px; }
p:last-child { margin-bottom: 0; }

blockquote {
  border-left: 3px solid var(--accent);
  padding: 8px 0 8px 16px;
  margin: 16px 0 0;
  color: var(--text);
  font-style: italic;
  background: linear-gradient(90deg, var(--accent-soft), transparent);
  border-radius: 0 6px 6px 0;
}

/* ========== CARDS ========== */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 22px 24px;
  margin-bottom: 16px;
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.3s var(--ease), transform 0.3s var(--ease), border-color 0.3s var(--ease);
}

.card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
  border-color: var(--border-strong);
}

/* ========== SLIDER / SCALE ========== */
.slider {
  width: 100%;
  margin: 18px 0 4px;
  -webkit-appearance: none;
  background: transparent;
  cursor: pointer;
}

.slider::-webkit-slider-runnable-track {
  height: 6px;
  background: var(--surface-2);
  border-radius: 3px;
}

.slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  height: 22px;
  width: 22px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  margin-top: -8px;
  border: 2px solid var(--surface);
  box-shadow: 0 2px 8px rgba(201, 100, 66, 0.4);
  transition: transform 0.15s var(--ease);
}

.slider::-webkit-slider-thumb:hover { transform: scale(1.15); }
.slider::-webkit-slider-thumb:active { transform: scale(1.05); }

.slider::-moz-range-track {
  height: 6px;
  background: var(--surface-2);
  border-radius: 3px;
}

.slider::-moz-range-thumb {
  height: 22px;
  width: 22px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--surface);
  box-shadow: 0 2px 8px rgba(201, 100, 66, 0.4);
}

.slider-ticks {
  display: flex;
  justify-content: space-between;
  font-size: 11px;
  color: var(--text-soft);
  margin-bottom: 18px;
  font-variant-numeric: tabular-nums;
}

.versus {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

.versus-card {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 16px 18px;
  position: relative;
  overflow: hidden;
  transition: transform 0.25s var(--ease);
}

.versus-card:hover { transform: scale(1.02); }

.versus-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.4s var(--ease);
}

.versus-card:hover::before { transform: scaleX(1); }

.versus-label {
  font-size: 11px;
  color: var(--text-muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  font-weight: 600;
}

.versus-status {
  font-size: 26px;
  font-weight: 700;
  margin: 4px 0 6px;
  transition: color 0.4s var(--ease), transform 0.4s var(--ease-bounce);
  letter-spacing: -0.02em;
}

.versus-status.bump { animation: bump 0.4s var(--ease-bounce); }

@keyframes bump {
  0%   { transform: scale(1); }
  50%  { transform: scale(1.12); }
  100% { transform: scale(1); }
}

.versus-detail {
  font-size: 13px;
  color: var(--text);
  line-height: 1.5;
}

/* ========== REASONS LIST ========== */
.reasons {
  margin: 8px 0 12px;
  padding-left: 20px;
}

.reasons li {
  margin-bottom: 10px;
  transition: transform 0.2s var(--ease);
}

.reasons li:hover { transform: translateX(3px); }

/* ========== CODE ========== */
.code-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin: 14px 0;
}

.code-label {
  font-size: 11px;
  color: var(--text-muted);
  margin-bottom: 8px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  font-weight: 600;
}

.code {
  font-family: var(--font-mono);
  font-size: 13px;
  background: var(--surface-2);
  padding: 14px 16px;
  border-radius: var(--radius);
  margin: 8px 0;
  overflow-x: auto;
  line-height: 1.7;
  border: 1px solid var(--border);
  position: relative;
  transition: border-color 0.2s var(--ease);
}

.code:hover { border-color: var(--border-strong); }

code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background: var(--surface-2);
  padding: 2px 6px;
  border-radius: 4px;
  border: 1px solid var(--border);
}

/* ========== COLLAPSIBLE ========== */
.collapsible {
  padding: 0;
  overflow: hidden;
}

.collapse-head {
  width: 100%;
  text-align: left;
  background: none;
  border: none;
  font-family: inherit;
  font-size: 15px;
  font-weight: 600;
  color: var(--text);
  padding: 18px 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  transition: background 0.2s var(--ease);
}

.collapse-head:hover { background: var(--surface-2); }

.chev {
  transition: transform 0.3s var(--ease-bounce);
  color: var(--text-muted);
  font-size: 13px;
}

.collapsible.open .chev { transform: rotate(180deg); }

.collapse-body {
  max-height: 0;
  overflow: hidden;
  padding: 0 24px;
  transition: max-height 0.4s var(--ease), padding 0.4s var(--ease);
}

.collapsible.open .collapse-body {
  max-height: 900px;
  padding: 0 24px 22px;
}

/* ========== ANATOMY ========== */
.anatomy {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.data-tbl {
  width: 100%;
  border-collapse: collapse;
  font-size: 13px;
  border-radius: var(--radius);
  overflow: hidden;
}

.data-tbl th,
.data-tbl td {
  text-align: left;
  padding: 9px 12px;
  border-bottom: 1px solid var(--border);
}

.data-tbl th {
  font-weight: 600;
  color: var(--text-muted);
  font-size: 11px;
  background: var(--surface-2);
  cursor: pointer;
  transition: all 0.2s var(--ease);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.data-tbl th:hover,
.data-tbl th.hl {
  background: var(--info-soft);
  color: var(--info);
  transform: translateY(-1px);
}

.data-tbl tbody tr {
  cursor: pointer;
  transition: all 0.2s var(--ease);
}

.data-tbl tbody tr:hover,
.data-tbl tbody tr.hl {
  background: var(--accent-soft);
}

.anatomy-explain {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 14px 16px;
  font-size: 14px;
  color: var(--text-muted);
  min-height: 22px;
  border-left: 3px solid var(--border-strong);
  transition: border-color 0.3s var(--ease);
}

.anatomy-explain.live { border-left-color: var(--accent); }

/* ========== FILTER BAR (PLAYGROUND) ========== */
.filter-bar {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 14px;
}

.fbtn {
  font-family: inherit;
  font-size: 13px;
  padding: 7px 14px;
  border-radius: 999px;
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text);
  cursor: pointer;
  transition: all 0.2s var(--ease);
  font-weight: 500;
}

.fbtn:hover {
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-1px);
}

.fbtn.on {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: white;
  border-color: var(--accent);
  box-shadow: 0 2px 8px rgba(201, 100, 66, 0.3);
}

.rt {
  width: 100%;
  border-collapse: collapse;
  font-size: 13px;
  margin-top: 8px;
  animation: fadeIn 0.3s var(--ease);
}

.rt th, .rt td {
  text-align: left;
  padding: 8px 10px;
  border-bottom: 1px solid var(--border);
}

.rt th {
  font-weight: 600;
  color: var(--text-muted);
  font-size: 11px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.rt tbody tr {
  transition: background 0.15s var(--ease);
}

.rt tbody tr:hover { background: var(--surface-2); }

.rt-count {
  font-size: 12px;
  color: var(--text-muted);
  margin-top: 8px;
  font-style: italic;
}

/* ========== TRANSACTION ========== */
.txn-steps {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 14px 18px;
  margin-bottom: 16px;
  border: 1px solid var(--border);
}

.txn-row {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 8px 0;
  font-size: 14px;
  transition: opacity 0.3s var(--ease);
}

.txn-dot {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--surface);
  border: 1.5px solid var(--border-strong);
  color: var(--text-muted);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  font-weight: 600;
  transition: all 0.3s var(--ease);
  flex-shrink: 0;
}

.txn-dot.done {
  background: var(--success);
  color: white;
  border-color: var(--success);
  animation: pop 0.4s var(--ease-bounce);
  box-shadow: 0 0 0 4px var(--success-soft);
}

.txn-dot.fail {
  background: var(--danger);
  color: white;
  border-color: var(--danger);
  animation: shake 0.4s var(--ease);
  box-shadow: 0 0 0 4px var(--danger-soft);
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20%, 60% { transform: translateX(-4px); }
  40%, 80% { transform: translateX(4px); }
}

.txn-dot.run {
  background: var(--info);
  color: white;
  border-color: var(--info);
  animation: pulse-ring 1s ease-in-out infinite;
}

@keyframes pulse-ring {
  0%   { box-shadow: 0 0 0 0 rgba(55, 138, 221, 0.5); }
  100% { box-shadow: 0 0 0 12px rgba(55, 138, 221, 0); }
}

.btn-row {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 14px;
}

.btn {
  font-family: inherit;
  font-size: 13px;
  padding: 9px 16px;
  border-radius: var(--radius);
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text);
  cursor: pointer;
  transition: all 0.2s var(--ease);
  font-weight: 500;
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at var(--ripple-x, 50%) var(--ripple-y, 50%), rgba(201,100,66,0.18) 0%, transparent 50%);
  opacity: 0;
  transition: opacity 0.4s var(--ease);
  pointer-events: none;
}

.btn:hover::before { opacity: 1; }
.btn:hover { border-color: var(--border-strong); transform: translateY(-1px); box-shadow: var(--shadow-sm); }
.btn:active { transform: translateY(0) scale(0.98); }

.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: white;
  border-color: var(--accent);
  box-shadow: 0 2px 8px rgba(201, 100, 66, 0.25);
}

.btn-primary:hover {
  border-color: var(--accent);
  box-shadow: 0 6px 16px rgba(201, 100, 66, 0.35);
}

.btn-danger {
  background: var(--warning-soft);
  color: var(--warning);
  border-color: var(--warning-soft);
}

.btn-danger:hover {
  border-color: var(--warning);
  background: var(--warning-soft);
  color: var(--warning);
}

.txn-status {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 12px 16px;
  font-size: 13px;
  font-family: var(--font-mono);
  min-height: 22px;
  border-left: 3px solid var(--border-strong);
  transition: border-color 0.3s var(--ease);
}

.txn-status .ok { color: var(--success); font-weight: 700; }
.txn-status .bad { color: var(--danger); font-weight: 700; }
.txn-status .warn { color: var(--warning); font-weight: 700; }

/* ========== ACID ========== */
.acid-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  margin-bottom: 16px;
}

.acid-card {
  font-family: inherit;
  text-align: left;
  background: var(--surface-2);
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  cursor: pointer;
  transition: all 0.3s var(--ease);
  color: var(--text);
  position: relative;
  overflow: hidden;
}

.acid-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.4s var(--ease);
}

.acid-card:hover {
  border-color: var(--accent);
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.acid-card:hover::before { transform: scaleX(1); }

.acid-card.active {
  border-color: var(--accent);
  background: linear-gradient(135deg, var(--accent-soft), var(--surface-2));
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.acid-card.active::before { transform: scaleX(1); }

.acid-letter {
  font-size: 32px;
  font-weight: 800;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  line-height: 1;
  letter-spacing: -0.04em;
}

.acid-name {
  font-size: 14px;
  font-weight: 600;
  margin-top: 8px;
}

.acid-rule {
  font-size: 12px;
  color: var(--text-muted);
  margin-top: 4px;
  line-height: 1.5;
}

.acid-detail {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 18px 20px;
  font-size: 14px;
  line-height: 1.7;
  color: var(--text);
  min-height: 60px;
  border-left: 3px solid var(--accent);
  transition: all 0.3s var(--ease);
}

.acid-detail.fresh { animation: fadeInUp 0.4s var(--ease); }

.acid-detail strong {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  font-weight: 700;
}

/* ========== OLTP / OLAP ========== */
.oltp-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

.oltp-col {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 20px 22px;
  position: relative;
  overflow: hidden;
  border: 1px solid var(--border);
  transition: all 0.3s var(--ease);
}

.oltp-col:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: var(--accent);
}

.oltp-col::before {
  content: '';
  position: absolute;
  top: -30px;
  right: -30px;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background: var(--accent-soft);
  opacity: 0.5;
  filter: blur(20px);
}

.oltp-col:nth-child(2)::before { background: var(--info-soft); }

.oltp-acro {
  font-size: 28px;
  font-weight: 800;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  letter-spacing: -0.02em;
  line-height: 1;
}

.oltp-col:nth-child(2) .oltp-acro {
  background: linear-gradient(135deg, var(--info), var(--purple));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.oltp-full {
  font-size: 14px;
  font-weight: 500;
  margin-top: 6px;
  color: var(--text);
}

.oltp-full strong {
  color: var(--accent);
  font-weight: 700;
}

.oltp-col:nth-child(2) .oltp-full strong { color: var(--info); }

.oltp-tag {
  font-size: 11px;
  color: var(--text-muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin: 6px 0 14px;
  font-weight: 600;
}

.oltp-col ul {
  margin: 0;
  padding-left: 20px;
  font-size: 14px;
}

.oltp-col li {
  margin-bottom: 8px;
  transition: transform 0.2s var(--ease);
}

.oltp-col li:hover { transform: translateX(2px); }

/* ========== QUIZ ========== */
.quiz-q {
  margin-bottom: 24px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--border);
}

.quiz-q:last-child { margin-bottom: 0; padding-bottom: 0; border-bottom: none; }

.quiz-q-text {
  font-weight: 600;
  margin-bottom: 12px;
  font-size: 15px;
}

.qopt {
  display: block;
  width: 100%;
  text-align: left;
  padding: 12px 16px;
  margin-bottom: 8px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  font-family: inherit;
  font-size: 14px;
  color: var(--text);
  cursor: pointer;
  transition: all 0.2s var(--ease);
  position: relative;
  overflow: hidden;
}

.qopt:hover:not(:disabled) {
  border-color: var(--accent);
  background: var(--accent-soft);
  transform: translateX(3px);
}

.qopt.correct {
  background: var(--success-soft);
  border-color: var(--success);
  color: var(--success);
  font-weight: 600;
  animation: correctPop 0.5s var(--ease-bounce);
}

@keyframes correctPop {
  0%   { transform: scale(1); }
  40%  { transform: scale(1.03); }
  100% { transform: scale(1); }
}

.qopt.wrong {
  background: var(--danger-soft);
  border-color: var(--danger);
  color: var(--danger);
  animation: shake 0.4s var(--ease);
}

.qopt:disabled { cursor: default; }

.score {
  margin-top: 16px;
  padding: 16px;
  border-radius: var(--radius);
  background: linear-gradient(135deg, var(--surface-2), var(--surface));
  font-size: 15px;
  font-weight: 600;
  text-align: center;
  border: 1px solid var(--border);
  animation: fadeInUp 0.5s var(--ease);
}

/* ========== LESSON FOOT ========== */
.lesson-foot {
  margin-top: 18px;
}

.complete-check {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 10px 16px;
  border-radius: var(--radius);
  background: var(--surface);
  border: 1px solid var(--border);
  font-size: 13px;
  color: var(--text-muted);
  cursor: pointer;
  transition: all 0.2s var(--ease);
  font-weight: 500;
}

.complete-check:hover {
  border-color: var(--success);
  background: var(--success-soft);
  color: var(--success);
}

.complete-check input { cursor: pointer; accent-color: var(--success); }

.complete-check input:checked + span {
  color: var(--success);
  font-weight: 600;
}

.site-foot {
  padding: 40px 0 60px;
  text-align: center;
  border-top: 1px solid var(--border);
  margin-top: 40px;
}

/* ========== CONFETTI ========== */
.confetti {
  position: fixed;
  width: 8px;
  height: 12px;
  pointer-events: none;
  z-index: 9999;
  border-radius: 1px;
  animation: confetti-fly 1.2s ease-out forwards;
}

@keyframes confetti-fly {
  0% {
    transform: translate(0, 0) rotate(0deg) scale(1);
    opacity: 1;
  }
  100% {
    transform: translate(var(--dx), var(--dy)) rotate(720deg) scale(0.4);
    opacity: 0;
  }
}

/* ========== GLOBAL ANIMATIONS ========== */
@keyframes fadeIn {
  from { opacity: 0; }
  to   { opacity: 1; }
}

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(12px); }
  to   { opacity: 1; transform: translateY(0); }
}

@keyframes fadeInDown {
  from { opacity: 0; transform: translateY(-12px); }
  to   { opacity: 1; transform: translateY(0); }
}

@keyframes fadeInLeft {
  from { opacity: 0; transform: translateX(-10px); }
  to   { opacity: 1; transform: translateX(0); }
}

@keyframes slideInLeft {
  from { transform: translateY(-50%) scaleY(0); }
  to   { transform: translateY(-50%) scaleY(1); }
}

/* ========== RESPONSIVE ========== */
@media (max-width: 900px) {
  body { grid-template-columns: 1fr; }
  .sidebar {
    position: relative;
    height: auto;
    width: 100%;
    border-right: none;
    border-bottom: 1px solid var(--border);
  }
  .main { padding: 32px 22px; }
  .acid-grid { grid-template-columns: repeat(2, 1fr); }
  .code-grid, .versus, .oltp-grid { grid-template-columns: 1fr; }
  h1 { font-size: 28px; }
}

/* ========== PUZZLE GAME ========== */
.puzzle-card { padding: 24px 26px; }

.puzzle-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 11px;
  color: var(--text-muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-weight: 700;
  margin-bottom: 16px;
}

.puzzle-num { color: var(--accent); }
.puzzle-score { font-variant-numeric: tabular-nums; }
#pscore {
  display: inline-block;
  color: var(--success);
  font-size: 16px;
  background: var(--success-soft);
  padding: 2px 10px;
  border-radius: 999px;
  margin-left: 6px;
  transition: transform 0.3s var(--ease-bounce);
}
#pscore.bump { animation: bump 0.4s var(--ease-bounce); }

.puzzle-goal {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  background: linear-gradient(135deg, var(--accent-soft), transparent);
  border-left: 3px solid var(--accent);
  padding: 14px 16px;
  border-radius: 0 var(--radius) var(--radius) 0;
  font-size: 15px;
  font-weight: 500;
  margin-bottom: 20px;
  line-height: 1.5;
}

.goal-label {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
  background: var(--surface);
  padding: 2px 8px;
  border-radius: 4px;
  flex-shrink: 0;
  margin-top: 2px;
}

.query-line {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding: 20px 18px;
  background: var(--surface-2);
  border-radius: var(--radius);
  border: 2px dashed var(--border-strong);
  min-height: 72px;
  align-items: center;
  margin-bottom: 18px;
  font-family: var(--font-mono);
  font-size: 14px;
}

.slot {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 8px 14px;
  border-radius: 8px;
  font-family: var(--font-mono);
  font-size: 14px;
  min-width: 54px;
  height: 36px;
  transition: all 0.25s var(--ease);
  position: relative;
  font-weight: 600;
}

.slot.fixed {
  background: transparent;
  color: var(--text-muted);
  letter-spacing: 0.03em;
}

.slot.empty {
  background: var(--surface);
  border: 1.5px dashed var(--border-strong);
  color: var(--text-soft);
  font-style: italic;
  font-weight: 400;
}

.slot.empty.hover {
  border-color: var(--accent);
  background: var(--accent-soft);
  transform: scale(1.08);
  border-style: solid;
  box-shadow: var(--shadow-glow);
}

.slot.filled {
  background: transparent;
  border: none;
  padding: 0;
  min-width: 0;
}

.palette-label {
  font-size: 11px;
  color: var(--text-muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-weight: 700;
  margin-bottom: 8px;
}

.chip-palette {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  padding: 18px;
  background: linear-gradient(135deg, var(--bg-grad-1), var(--bg-grad-2));
  border-radius: var(--radius);
  border: 1px solid var(--border);
  margin-bottom: 18px;
  min-height: 72px;
}

.chip {
  display: inline-flex;
  align-items: center;
  padding: 8px 14px;
  border-radius: 8px;
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 700;
  cursor: grab;
  user-select: none;
  touch-action: none;
  transition: transform 0.2s var(--ease), box-shadow 0.2s var(--ease);
  box-shadow: 0 2px 4px rgba(0,0,0,0.08);
  position: relative;
  z-index: 1;
}

.chip:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 16px rgba(0,0,0,0.14);
}

.chip.dragging {
  cursor: grabbing;
  z-index: 1000;
  opacity: 0.92;
  box-shadow: 0 12px 28px rgba(0,0,0,0.25);
}

.chip.locked {
  cursor: default;
  box-shadow: none;
}

.chip.locked:hover { transform: none; box-shadow: none; }

.chip.snap { animation: chipSnap 0.45s var(--ease-bounce); }

@keyframes chipSnap {
  0%   { transform: scale(1.2); }
  60%  { transform: scale(0.92); }
  100% { transform: scale(1); }
}

.chip.reject { animation: chipReject 0.4s var(--ease); }

@keyframes chipReject {
  0%, 100% { transform: translate(0, 0); }
  20%      { transform: translate(-8px, 0); }
  40%      { transform: translate(8px, 0); }
  60%      { transform: translate(-4px, 0); }
  80%      { transform: translate(4px, 0); }
}

.chip.keyword  { background: var(--purple-soft); color: var(--purple); border: 1px solid var(--purple); }
.chip.column   { background: var(--info-soft);   color: var(--info);   border: 1px solid var(--info); }
.chip.operator { background: var(--warning-soft);color: var(--warning);border: 1px solid var(--warning); }
.chip.value    { background: var(--success-soft);color: var(--success);border: 1px solid var(--success); }

.puzzle-buttons {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 12px;
}

.hint-box {
  background: var(--warning-soft);
  border-radius: var(--radius);
  padding: 12px 16px;
  font-size: 13px;
  color: var(--warning);
  margin-bottom: 12px;
  display: none;
  border-left: 3px solid var(--warning);
  animation: fadeInUp 0.3s var(--ease);
}

.hint-box.show { display: block; }

.puzzle-result { margin-top: 12px; }

.puzzle-win {
  text-align: center;
  padding: 36px 20px;
  background: linear-gradient(135deg, var(--success-soft), var(--accent-soft));
  border-radius: var(--radius-lg);
  border: 1px solid var(--success);
  margin-top: 18px;
  animation: trophyIn 0.7s var(--ease-bounce);
}

@keyframes trophyIn {
  from { opacity: 0; transform: scale(0.7) translateY(20px); }
  to   { opacity: 1; transform: scale(1) translateY(0); }
}

.puzzle-win-emoji {
  font-size: 64px;
  line-height: 1;
  animation: float 2.5s ease-in-out infinite;
}

.puzzle-win-title {
  font-size: 24px;
  font-weight: 800;
  margin: 12px 0 6px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.puzzle-win-stat {
  font-size: 14px;
  color: var(--text-muted);
}

/* ========== RESTAURANT ANALOGY (L2) ========== */
.analogy {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 16px;
  align-items: stretch;
  margin-top: 12px;
}

.analogy-side {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 20px;
  border: 1px solid var(--border);
  transition: all 0.3s var(--ease);
}

.analogy-side:hover { transform: translateY(-3px); box-shadow: var(--shadow-md); }

.analogy-win {
  background: linear-gradient(135deg, var(--success-soft), var(--surface-2));
  border-color: var(--success);
}

.analogy-emoji { font-size: 38px; line-height: 1; margin-bottom: 8px; }

.analogy-title { font-size: 16px; font-weight: 700; margin-bottom: 4px; }

.analogy-sub {
  font-size: 11px;
  color: var(--text-muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  font-weight: 600;
  margin-bottom: 12px;
}

.analogy-side ul {
  padding-left: 20px;
  margin: 0 0 10px;
  font-size: 13px;
}

.analogy-side li { margin-bottom: 4px; }

.analogy-vs {
  align-self: center;
  font-size: 18px;
  font-weight: 700;
  color: var(--text-muted);
  letter-spacing: 0.04em;
}

/* ========== TIMELINE (SEQUEL history) ========== */
.timeline {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  position: relative;
  padding-top: 12px;
}

.timeline::before {
  content: '';
  position: absolute;
  top: 22px;
  left: 6%;
  right: 6%;
  height: 2px;
  background: linear-gradient(90deg, var(--accent), var(--purple));
  border-radius: 2px;
}

.tl-node {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 38px 14px 14px;
  position: relative;
  border: 1px solid var(--border);
  transition: all 0.3s var(--ease);
}

.tl-node:hover {
  transform: translateY(-3px);
  border-color: var(--accent);
  box-shadow: var(--shadow-md);
}

.tl-dot {
  position: absolute;
  top: -2px;
  left: 50%;
  transform: translateX(-50%);
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 13px;
  border: 3px solid var(--surface);
  box-shadow: 0 2px 8px rgba(201, 100, 66, 0.3);
}

.tl-year {
  font-size: 11px;
  color: var(--accent);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  font-weight: 700;
  margin-bottom: 4px;
}

.tl-title {
  font-size: 13px;
  font-weight: 700;
  margin-bottom: 6px;
  line-height: 1.3;
}

.tl-body {
  font-size: 12px;
  color: var(--text-muted);
  line-height: 1.5;
}

/* ========== DB INTERNALS — parts grid ========== */
.parts-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  margin-top: 12px;
}

.part-card {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 16px;
  border: 1px solid var(--border);
  transition: all 0.3s var(--ease);
}

.part-card:hover {
  transform: translateY(-3px);
  border-color: var(--accent);
  box-shadow: var(--shadow-md);
}

.part-icon { font-size: 26px; line-height: 1; margin-bottom: 8px; }
.part-name { font-size: 15px; font-weight: 700; margin-bottom: 6px; }
.part-desc { font-size: 13px; color: var(--text-muted); line-height: 1.5; }

/* ========== DB INTERNALS — find game ========== */
.search-grid {
  display: grid;
  grid-template-columns: repeat(10, 1fr);
  gap: 4px;
  margin: 14px 0;
  padding: 12px;
  background: var(--surface-2);
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.sg-cell {
  aspect-ratio: 1;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 4px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 10px;
  font-weight: 600;
  color: var(--text-muted);
  font-variant-numeric: tabular-nums;
  transition: all 0.15s var(--ease);
}

.sg-cell.scan {
  background: var(--info);
  color: white;
  border-color: var(--info);
  transform: scale(1.05);
}

.sg-cell.skip {
  background: var(--surface-2);
  opacity: 0.4;
}

.sg-cell.target {
  background: var(--success);
  color: white;
  border-color: var(--success);
  transform: scale(1.15);
  box-shadow: 0 0 0 4px var(--success-soft);
  z-index: 2;
}

.sg-cell.btree-hop {
  background: var(--purple);
  color: white;
  border-color: var(--purple);
  animation: pop 0.4s var(--ease-bounce);
}

.search-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
  margin: 14px 0;
}

.stat-card {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 12px;
  text-align: center;
  border: 1px solid var(--border);
}

.stat-label {
  font-size: 11px;
  color: var(--text-muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  font-weight: 600;
  margin-bottom: 4px;
}

.stat-num {
  font-size: 24px;
  font-weight: 800;
  color: var(--text);
  font-variant-numeric: tabular-nums;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.search-result {
  margin-top: 12px;
  padding: 14px 16px;
  background: var(--surface-2);
  border-radius: var(--radius);
  font-size: 13px;
  min-height: 20px;
  border-left: 3px solid var(--border-strong);
  transition: border-color 0.3s var(--ease);
}

.search-result.win { border-left-color: var(--success); }

/* ========== RELATIONAL vs NoSQL — use case picker ========== */
#use-cases { display: flex; flex-direction: column; gap: 10px; margin-top: 12px; }

.uc-card {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 14px 16px;
  border: 1px solid var(--border);
}

.uc-q { font-size: 14px; font-weight: 600; margin-bottom: 10px; }

.uc-options { display: flex; gap: 8px; flex-wrap: wrap; }

.uc-opt {
  font-family: inherit;
  font-size: 13px;
  padding: 7px 14px;
  border-radius: 999px;
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text);
  cursor: pointer;
  transition: all 0.2s var(--ease);
  font-weight: 500;
}

.uc-opt:hover:not(:disabled) {
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-1px);
}

.uc-opt.correct {
  background: var(--success-soft);
  border-color: var(--success);
  color: var(--success);
  font-weight: 700;
}

.uc-opt.wrong {
  background: var(--danger-soft);
  border-color: var(--danger);
  color: var(--danger);
  animation: shake 0.4s var(--ease);
}

.uc-why {
  margin-top: 10px;
  padding: 10px 12px;
  background: var(--surface);
  border-radius: 6px;
  font-size: 12px;
  color: var(--text-muted);
  border-left: 3px solid var(--accent);
  display: none;
  animation: fadeInUp 0.3s var(--ease);
}

.uc-why.show { display: block; }

.uc-score {
  margin-top: 12px;
  padding: 12px;
  border-radius: var(--radius);
  background: var(--surface-2);
  text-align: center;
  font-size: 14px;
  font-weight: 600;
  color: var(--text-muted);
  font-variant-numeric: tabular-nums;
}

/* ========== OLTP/OLAP comparison table ========== */
.comparison-tbl {
  width: 100%;
  border-collapse: collapse;
  font-size: 13px;
  margin-top: 8px;
  border-radius: var(--radius);
  overflow: hidden;
}

.comparison-tbl th {
  background: var(--surface-2);
  text-align: left;
  padding: 12px 14px;
  font-weight: 700;
  font-size: 12px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--text);
  border-bottom: 2px solid var(--border);
}

.comparison-tbl th:nth-child(2) { color: var(--accent); }
.comparison-tbl th:nth-child(3) { color: var(--info); }

.comparison-tbl td {
  padding: 10px 14px;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}

.comparison-tbl tr:last-child td { border-bottom: none; }

.comparison-tbl tbody tr:hover { background: var(--surface-2); }

.comparison-tbl td:first-child {
  font-weight: 700;
  color: var(--text-muted);
  font-size: 12px;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

/* ========== DBMS vs RDBMS — hierarchy ========== */
.hierarchy {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  padding: 20px 0;
}

.hier-row {
  display: flex;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
}

.hier-row-children {
  width: 100%;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}

.hier-line {
  width: 80%;
  height: 24px;
  position: relative;
}

.hier-line::before {
  content: '';
  position: absolute;
  top: 0;
  left: 50%;
  width: 2px;
  height: 12px;
  background: var(--border-strong);
}

.hier-line::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 12.5%;
  right: 12.5%;
  height: 2px;
  background: var(--border-strong);
}

.hier-node {
  background: var(--surface-2);
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 18px;
  text-align: center;
  cursor: pointer;
  transition: all 0.25s var(--ease);
  min-width: 110px;
}

.hier-node.big { padding: 18px 32px; }

.hier-node:hover {
  transform: translateY(-3px);
  border-color: var(--accent);
  box-shadow: var(--shadow-md);
}

.hier-node.active {
  background: linear-gradient(135deg, var(--accent-soft), var(--surface));
  border-color: var(--accent);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.hier-node.featured {
  border-color: var(--purple);
  background: var(--purple-soft);
}

.hier-node.featured .hier-title { color: var(--purple); }

.hier-title { font-size: 15px; font-weight: 700; }
.hier-node.big .hier-title { font-size: 18px; }

.hier-sub {
  font-size: 11px;
  color: var(--text-muted);
  margin-top: 2px;
  letter-spacing: 0.03em;
}

.hier-detail {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 16px 18px;
  font-size: 14px;
  line-height: 1.6;
  color: var(--text);
  min-height: 60px;
  border-left: 3px solid var(--accent);
  margin-top: 14px;
  transition: all 0.3s var(--ease);
}

.hier-detail.fresh { animation: fadeInUp 0.3s var(--ease); }
.hier-detail strong { color: var(--accent); }

.rule-box {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 18px;
  border-left: 3px solid var(--success);
}

.rule-line {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 8px;
}

.rule-check {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--success);
  color: white;
  font-weight: 800;
  font-size: 14px;
}

.rule-cross {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--danger);
  color: white;
  font-weight: 800;
  font-size: 14px;
}

/* ========== RESPONSIVE for new components ========== */
@media (max-width: 900px) {
  .analogy { grid-template-columns: 1fr; }
  .analogy-vs { padding: 6px 0; }
  .timeline { grid-template-columns: repeat(2, 1fr); }
  .timeline::before { display: none; }
  .parts-grid { grid-template-columns: 1fr; }
  .search-grid { grid-template-columns: repeat(8, 1fr); }
  .hier-row-children { grid-template-columns: repeat(2, 1fr); }
  .search-stats { grid-template-columns: repeat(3, 1fr); }
}

/* ========== WHERE TO RUN — option cards ========== */
.run-options {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-top: 12px;
}

.run-card {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 18px;
  border: 1px solid var(--border);
  transition: all 0.3s var(--ease);
}

.run-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-md); }

.run-win {
  background: linear-gradient(135deg, var(--success-soft), var(--surface-2));
  border-color: var(--success);
}

.run-icon { font-size: 30px; line-height: 1; margin-bottom: 8px; }
.run-name { font-size: 16px; font-weight: 700; }
.run-sub {
  font-size: 11px;
  color: var(--text-muted);
  letter-spacing: 0.04em;
  margin: 2px 0 12px;
}

.run-pros { list-style: none; padding: 0; margin: 0; font-size: 13px; }
.run-pros li {
  padding: 4px 0 4px 22px;
  position: relative;
  line-height: 1.4;
}
.run-pros li.pro::before {
  content: '✓';
  position: absolute;
  left: 0;
  color: var(--success);
  font-weight: 800;
}
.run-pros li.con::before {
  content: '✗';
  position: absolute;
  left: 0;
  color: var(--danger);
  font-weight: 800;
}

/* ========== LATENCY DEMO ========== */
.latency-demo {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin: 14px 0;
}

.lat-row {
  display: grid;
  grid-template-columns: 110px 1fr 70px;
  gap: 12px;
  align-items: center;
}

.lat-label { font-size: 13px; font-weight: 600; }

.lat-track {
  position: relative;
  height: 44px;
  background: var(--surface-2);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 12px;
  overflow: hidden;
}

.lat-laptop, .lat-server { font-size: 22px; z-index: 2; }

.lat-packet {
  position: absolute;
  left: 32px;
  top: 50%;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--info);
  transform: translateY(-50%);
  opacity: 0;
  box-shadow: 0 0 8px var(--info);
}

.lat-packet.local { background: var(--success); box-shadow: 0 0 8px var(--success); }

.lat-packet.travel-online {
  animation: packetOnline 1.6s var(--ease) forwards;
}

.lat-packet.travel-local {
  animation: packetLocal 0.18s linear forwards;
}

@keyframes packetOnline {
  0%   { opacity: 1; left: 32px; }
  45%  { opacity: 1; left: calc(100% - 44px); }
  55%  { opacity: 1; left: calc(100% - 44px); }
  100% { opacity: 1; left: 32px; }
}

@keyframes packetLocal {
  0%   { opacity: 1; left: 32px; }
  50%  { opacity: 1; left: 80px; }
  100% { opacity: 1; left: 32px; }
}

.lat-time {
  font-size: 14px;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  text-align: right;
  color: var(--text-muted);
}

/* ========== DOCKER vs NATIVE ========== */
.docker-vs {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 14px;
  align-items: center;
  margin-top: 12px;
}

.dv-side {
  border-radius: var(--radius);
  padding: 16px 18px;
  border: 1px solid var(--border);
}

.dv-bad { background: var(--danger-soft); border-color: var(--danger); }
.dv-good { background: var(--success-soft); border-color: var(--success); }

.dv-label {
  font-size: 14px;
  font-weight: 700;
  margin-bottom: 10px;
}
.dv-bad .dv-label { color: var(--danger); }
.dv-good .dv-label { color: var(--success); }

.dv-side ul { margin: 0; padding-left: 18px; font-size: 13px; }
.dv-side li { margin-bottom: 6px; }

.dv-arrow {
  font-size: 24px;
  color: var(--text-muted);
  font-weight: 700;
}

/* ========== IMAGE vs CONTAINER ========== */
.iv-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin: 12px 0;
}

.iv-card {
  font-family: inherit;
  background: var(--surface-2);
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  cursor: pointer;
  transition: all 0.25s var(--ease);
  color: var(--text);
  text-align: center;
}

.iv-card:hover { transform: translateY(-3px); border-color: var(--accent); box-shadow: var(--shadow-md); }
.iv-card.active {
  background: linear-gradient(135deg, var(--accent-soft), var(--surface-2));
  border-color: var(--accent);
}

.iv-icon { font-size: 30px; line-height: 1; }
.iv-name { font-size: 16px; font-weight: 700; margin-top: 6px; }
.iv-tag { font-size: 12px; color: var(--text-muted); margin-top: 2px; }

.iv-detail {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 16px 18px;
  font-size: 14px;
  line-height: 1.6;
  border-left: 3px solid var(--accent);
  min-height: 50px;
  transition: all 0.3s var(--ease);
}
.iv-detail.fresh { animation: fadeInUp 0.3s var(--ease); }
.iv-detail strong { color: var(--accent); }

/* ========== DOCKER FORM ========== */
.docker-form {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin: 12px 0;
}

.df-row { display: flex; flex-direction: column; gap: 5px; }

.df-row label {
  font-size: 12px;
  font-weight: 600;
  color: var(--text-muted);
  font-family: var(--font-mono);
}

.df-row input {
  font-family: var(--font-mono);
  font-size: 13px;
  padding: 9px 12px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  transition: all 0.2s var(--ease);
}

.df-row input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: var(--shadow-glow);
}

.df-row input.field-err {
  border-color: var(--danger);
  background: var(--danger-soft);
}

.df-result {
  margin-top: 12px;
  padding: 14px 16px;
  background: var(--surface-2);
  border-radius: var(--radius);
  font-size: 13px;
  border-left: 3px solid var(--border-strong);
  transition: border-color 0.3s var(--ease);
  line-height: 1.6;
}

.df-result.ok { border-left-color: var(--success); }
.df-result.warn { border-left-color: var(--warning); }
.df-result pre {
  font-family: var(--font-mono);
  font-size: 12px;
  background: var(--surface);
  padding: 10px 12px;
  border-radius: 6px;
  margin: 8px 0 0;
  overflow-x: auto;
  border: 1px solid var(--border);
  white-space: pre-wrap;
}

/* ========== BEEKEEPER WIZARD ========== */
.bk-wizard {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 8px 16px;
  margin: 12px 0;
  border: 1px solid var(--border);
}

.bk-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 9px 0;
  border-bottom: 1px solid var(--border);
  font-size: 13px;
}
.bk-row:last-child { border-bottom: none; }
.bk-row label { color: var(--text-muted); font-weight: 600; }
.bk-val { font-family: var(--font-mono); font-weight: 600; }

.bk-result {
  margin-top: 12px;
  font-size: 13px;
  min-height: 18px;
  font-weight: 600;
}
.bk-result.ok { color: var(--success); }

/* ========== TIP CARD ========== */
.tip-card {
  display: flex;
  gap: 14px;
  align-items: flex-start;
  background: var(--warning-soft);
  border-color: var(--warning);
}
.tip-card .tip-icon { font-size: 24px; line-height: 1.3; flex-shrink: 0; }
.tip-card strong { color: var(--warning); }

/* ========== RESPONSIVE for setup components ========== */
@media (max-width: 900px) {
  .run-options { grid-template-columns: 1fr; }
  .docker-vs { grid-template-columns: 1fr; }
  .dv-arrow { transform: rotate(90deg); justify-self: center; }
  .docker-form { grid-template-columns: 1fr; }
  .lat-row { grid-template-columns: 80px 1fr 56px; }
}

/* ========== MODULE SUB-NAV ========== */
.subnav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 32px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--border);
}

.subnav a {
  font-size: 12.5px;
  padding: 6px 12px;
  border-radius: 999px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  color: var(--text-muted);
  text-decoration: none;
  transition: all 0.2s var(--ease);
  font-weight: 500;
}

.subnav a:hover {
  color: var(--accent);
  border-color: var(--accent);
  transform: translateY(-1px);
}

/* ========== SUB-SECTION ========== */
.subsection {
  margin-bottom: 48px;
  scroll-margin-top: 24px;
}

.sub-head {
  margin-bottom: 16px;
  padding-top: 8px;
}

.sub-tag {
  display: inline-block;
  font-size: 10.5px;
  font-weight: 700;
  color: var(--accent);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 6px;
  padding: 3px 9px;
  background: var(--accent-soft);
  border-radius: 999px;
}

.sub-head h2 {
  font-size: 22px;
  font-weight: 700;
  margin: 0;
  letter-spacing: -0.01em;
}

/* ========== GENERIC CLICK-REVEAL CARDS ========== */
.click-grid {
  display: grid;
  gap: 10px;
  margin: 12px 0;
}
.click-grid.five { grid-template-columns: repeat(5, 1fr); }
.click-grid.three { grid-template-columns: repeat(3, 1fr); }

.click-card {
  font-family: inherit;
  background: var(--surface-2);
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 12px;
  cursor: pointer;
  transition: all 0.25s var(--ease);
  color: var(--text);
  text-align: center;
}

.click-card:hover {
  transform: translateY(-3px);
  border-color: var(--accent);
  box-shadow: var(--shadow-md);
}

.click-card.active {
  background: linear-gradient(135deg, var(--accent-soft), var(--surface-2));
  border-color: var(--accent);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.cc-acro {
  font-size: 20px;
  font-weight: 800;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  letter-spacing: -0.02em;
}

.cc-name { font-size: 14px; font-weight: 700; }
.cc-tag { font-size: 11px; color: var(--text-muted); margin-top: 3px; }

.click-detail {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 16px 18px;
  font-size: 14px;
  line-height: 1.6;
  border-left: 3px solid var(--accent);
  min-height: 50px;
  transition: all 0.3s var(--ease);
}
.click-detail.fresh { animation: fadeInUp 0.3s var(--ease); }
.click-detail strong { color: var(--accent); }
.click-detail code {
  font-family: var(--font-mono);
  font-size: 0.88em;
  background: var(--surface);
  padding: 1px 5px;
  border-radius: 4px;
  border: 1px solid var(--border);
}

/* ========== CLASSIFY GAME (generic) ========== */
.cg-label {
  font-size: 11px;
  color: var(--text-muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  font-weight: 700;
  margin-right: 8px;
}
.cg-prompt {
  font-family: var(--font-mono);
  font-weight: 700;
  background: var(--surface);
  padding: 3px 10px;
  border-radius: 6px;
  border: 1px solid var(--border-strong);
}

/* ========== KEY TABLES VISUAL ========== */
.key-tables {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: center;
  margin: 14px 0;
}

.key-tbl {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.key-tbl-name {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 13px;
  padding: 8px 12px;
  background: var(--accent-soft);
  color: var(--accent);
  border-bottom: 1px solid var(--border);
}

.key-col {
  font-family: var(--font-mono);
  font-size: 12.5px;
  padding: 8px 12px;
  border-bottom: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 8px;
}
.key-col:last-child { border-bottom: none; }
.key-col.is-pk { background: var(--success-soft); }
.key-col.is-fk { background: var(--info-soft); }

.key-badge {
  font-size: 9.5px;
  font-weight: 800;
  padding: 2px 6px;
  border-radius: 4px;
  letter-spacing: 0.04em;
}
.key-badge.pk { background: var(--success); color: white; }
.key-badge.fk { background: var(--info); color: white; }

.key-link {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  color: var(--info);
  text-align: center;
  white-space: nowrap;
}

/* ========== NULL vs 0 vs '' CARDS ========== */
.null-cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
}

.null-card {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  transition: all 0.3s var(--ease);
}
.null-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-md); border-color: var(--accent); }

.null-tag {
  font-family: var(--font-mono);
  font-size: 20px;
  font-weight: 800;
  color: var(--accent);
  margin-bottom: 8px;
}
.null-desc { font-size: 13px; line-height: 1.5; }
.null-ex { font-size: 12px; color: var(--text-muted); margin-top: 8px; font-style: italic; }

/* ========== QUERY LIFECYCLE PIPELINE ========== */
.pipeline {
  display: grid;
  grid-template-columns: 1fr auto 1fr auto 1fr;
  gap: 8px;
  align-items: stretch;
  margin: 14px 0;
}

.pipe-stage {
  background: var(--surface-2);
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 14px;
  text-align: center;
  transition: all 0.35s var(--ease);
}

.pipe-stage.active {
  border-color: var(--info);
  background: var(--info-soft);
  transform: translateY(-3px);
  box-shadow: 0 0 0 4px var(--info-soft);
}
.pipe-stage.done {
  border-color: var(--success);
  background: var(--success-soft);
}

.pipe-num {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--surface);
  border: 1.5px solid var(--border-strong);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 13px;
  margin: 0 auto 8px;
  transition: all 0.3s var(--ease);
}
.pipe-stage.active .pipe-num { background: var(--info); color: white; border-color: var(--info); }
.pipe-stage.done .pipe-num { background: var(--success); color: white; border-color: var(--success); }

.pipe-title { font-size: 15px; font-weight: 700; }
.pipe-desc { font-size: 12px; color: var(--text-muted); margin-top: 4px; line-height: 1.4; }

.pipe-arrow {
  align-self: center;
  font-size: 18px;
  color: var(--text-muted);
  font-weight: 700;
}

.lifecycle-status {
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 12px 16px;
  font-size: 13px;
  font-family: var(--font-mono);
  min-height: 20px;
  border-left: 3px solid var(--border-strong);
  transition: border-color 0.3s var(--ease);
}
.lifecycle-status .ok { color: var(--success); font-weight: 700; }

/* ========== RESPONSIVE for module components ========== */
@media (max-width: 900px) {
  .click-grid.five { grid-template-columns: repeat(2, 1fr); }
  .click-grid.three { grid-template-columns: 1fr; }
  .key-tables { grid-template-columns: 1fr; }
  .key-link { transform: rotate(90deg); }
  .null-cards { grid-template-columns: 1fr; }
  .pipeline { grid-template-columns: 1fr; }
  .pipe-arrow { transform: rotate(90deg); justify-self: center; }
}

/* ========== QUERY FUNDAMENTALS CONTROLS ========== */
.control-row {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  align-items: center;
  margin-bottom: 12px;
}

select {
  font-family: inherit;
  font-size: 13px;
  padding: 7px 10px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
  transition: border-color 0.2s var(--ease);
}
select:hover { border-color: var(--border-strong); }
select:focus { outline: none; border-color: var(--accent); box-shadow: var(--shadow-glow); }

.qinput {
  font-family: var(--font-mono);
  font-size: 13px;
  padding: 8px 12px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  transition: border-color 0.2s var(--ease);
  min-width: 140px;
}
.qinput:focus { outline: none; border-color: var(--accent); box-shadow: var(--shadow-glow); }

.col-toggles {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 12px;
}
.col-toggles label {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 7px 13px;
  border-radius: 999px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  font-family: var(--font-mono);
  font-size: 13px;
  cursor: pointer;
  transition: all 0.2s var(--ease);
}
.col-toggles label:hover { border-color: var(--accent); }
.col-toggles input { accent-color: var(--accent); cursor: pointer; }

.exec-order {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: 8px;
}
.exec-step {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 10px 14px;
  font-size: 13px;
  font-weight: 600;
  font-family: var(--font-mono);
}
.exec-step em { display: block; font-style: normal; font-weight: 400; font-size: 11px; color: var(--text-muted); font-family: var(--font); margin-top: 2px; }
.exec-sep { color: var(--text-muted); font-weight: 700; }

.logic-conds {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 12px;
}
.logic-cond {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 10px 14px;
  font-size: 13px;
}
.logic-pick { display: inline-flex; gap: 6px; }
.logic-not {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--text-muted);
  margin-bottom: 12px;
  cursor: pointer;
}
.logic-not input { accent-color: var(--accent); cursor: pointer; }

.rt tr.row-pass { background: var(--success-soft); }
.rt tr.row-pass td:first-child { color: var(--success); font-weight: 700; }
.rt tr.row-fail { opacity: 0.4; }
.rt tr.row-fail td:first-child { color: var(--danger); font-weight: 700; }
.rt tr { transition: background 0.2s var(--ease), opacity 0.2s var(--ease); }

.cell-null {
  color: var(--text-soft);
  font-style: italic;
  font-size: 12px;
}

.wildcard-legend {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  margin-bottom: 12px;
}
.wildcard-legend .fbtn { font-family: var(--font-mono); font-size: 12px; }

.cat-badge {
  display: inline-block;
  padding: 2px 10px;
  border-radius: 999px;
  font-size: 12px;
  font-weight: 600;
}
.cat-budget { background: var(--success-soft); color: var(--success); }
.cat-mid { background: var(--warning-soft); color: var(--warning); }
.cat-premium { background: var(--info-soft); color: var(--info); }
.cat-missing { background: var(--surface-2); color: var(--text-soft); font-style: italic; }

.hl-pos {
  background: var(--warning-soft);
  color: var(--warning);
  font-weight: 700;
  border-radius: 3px;
  padding: 0 2px;
}
.mono { font-family: var(--font-mono); }

/* ========== MODULE 11: MERGING QUERY RESULTS ========== */
.dual-source {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 18px;
}
@media (max-width: 640px) { .dual-source { grid-template-columns: 1fr; } }
.src-label {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 6px;
}
.seg {
  display: inline-flex;
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow: hidden;
}
.seg-btn {
  border: none;
  background: var(--surface);
  color: var(--text-soft);
  padding: 6px 14px;
  font-size: 13px;
  font-weight: 600;
  font-family: var(--font-mono);
  cursor: pointer;
  transition: background 0.2s var(--ease), color 0.2s var(--ease);
}
.seg-btn + .seg-btn { border-left: 1px solid var(--border); }
.seg-btn.active { background: var(--accent); color: #fff; }
.seg-btn:not(.active):hover { background: var(--surface-2); }
.rt tr.row-removed td { opacity: 0.45; text-decoration: line-through; }
.rt tr.row-removed { background: var(--danger-soft); }
.src-cell { font-family: var(--font-mono); font-size: 12px; color: var(--text-muted); }
.merge-note, .merge-total {
  margin-top: 10px;
  font-size: 14px;
  color: var(--text-soft);
}
.merge-total { font-size: 15px; }
.set-buckets {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin: 14px 0;
}
@media (max-width: 560px) { .set-buckets { grid-template-columns: 1fr; } }
.set-bucket {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px;
  background: var(--surface);
  opacity: 0.4;
  transition: opacity 0.25s var(--ease), border-color 0.25s var(--ease), box-shadow 0.25s var(--ease);
}
.set-bucket.active {
  opacity: 1;
  border-color: var(--accent);
  box-shadow: var(--shadow-md);
}
.set-bucket-title {
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--text-muted);
  margin-bottom: 6px;
}
.set-bucket.active .set-bucket-title { color: var(--accent); }
.set-bucket-body {
  font-family: var(--font-mono);
  font-size: 14px;
  color: var(--text);
  min-height: 18px;
}
.decision-list {
  margin: 4px 0 0;
  padding-left: 20px;
  line-height: 1.7;
  color: var(--text-soft);
}
.decision-list li { margin-bottom: 4px; }

/* ========== MODULE 13: PERMISSIONS ========== */
.pm-priv-row { flex-wrap: wrap; gap: 10px 18px; }
.pm-check {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--text);
  cursor: pointer;
  user-select: none;
  padding: 6px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--surface);
  transition: border-color 0.2s var(--ease), background 0.2s var(--ease);
}
.pm-check:hover { border-color: var(--accent); }
.pm-check input { accent-color: var(--accent); cursor: pointer; }
.pm-check-special { border-style: dashed; color: var(--warning); }

.pm-ops { display: flex; flex-direction: column; gap: 8px; margin-top: 14px; }
.pm-op {
  display: flex;
  align-items: stretch;
  gap: 12px;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--surface);
}
.pm-badge {
  flex-shrink: 0;
  align-self: flex-start;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.04em;
  padding: 4px 9px;
  border-radius: 6px;
  margin-top: 2px;
}
.pm-badge.ok { background: var(--success-soft); color: var(--success); }
.pm-badge.no { background: var(--danger-soft); color: var(--danger); }
.pm-op-body { min-width: 0; flex: 1; }
.pm-op-sql {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--text);
  margin: 0;
  white-space: pre-wrap;
  word-break: break-word;
}
.pm-op-why { font-size: 12.5px; color: var(--text-muted); margin-top: 4px; }

/* scope visualizer */
.pm-tree { margin: 14px 0; }
.pm-server {
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 14px;
  background: var(--surface);
}
.pm-node-label { font-family: var(--font-mono); font-size: 13px; font-weight: 600; color: var(--text); }
.pm-server > .pm-node-label { margin-bottom: 12px; }
.pm-db {
  border: 1px dashed var(--border);
  border-radius: 10px;
  padding: 10px 12px;
  margin-top: 10px;
  opacity: 0.5;
  transition: opacity 0.25s var(--ease), border-color 0.25s var(--ease), background 0.25s var(--ease);
}
.pm-db.on {
  opacity: 1;
  border-color: var(--success);
  border-style: solid;
  background: var(--success-soft);
}
.pm-tables { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 10px; }
.pm-tbl {
  font-family: var(--font-mono);
  font-size: 12.5px;
  padding: 5px 10px;
  border-radius: 7px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text-muted);
  transition: all 0.25s var(--ease);
}
.pm-tbl.on {
  border-color: var(--success);
  color: var(--success);
  font-weight: 600;
  box-shadow: 0 0 0 2px var(--success-soft);
}

/* ========== MODULE 14: TRANSACTIONS ========== */
/* connection pool viz */
.tx-pool { display: flex; flex-direction: column; gap: 8px; margin: 14px 0; }
.tx-pool-row {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  padding: 9px 12px;
  border: 1px solid var(--border);
  border-radius: 9px;
  background: var(--surface);
  font-family: var(--font-mono);
  font-size: 13px;
}
.tx-pool-row.go { animation: txPoolIn 0.4s var(--ease) backwards; animation-delay: var(--d, 0s); }
@keyframes txPoolIn { from { opacity: 0; transform: translateX(-12px); } to { opacity: 1; transform: none; } }
.tx-req { font-weight: 700; color: var(--text); }
.tx-arrow { color: var(--text-muted); }
.tx-conn { color: var(--info); font-weight: 600; }
.tx-lane { font-size: 12px; padding: 3px 9px; border-radius: 6px; margin-left: auto; }
.tx-lane.parallel { background: var(--success-soft); color: var(--success); }
.tx-lane.queued { background: var(--warning-soft); color: var(--warning); }

/* commit/rollback simulator */
.tx-sim-controls { flex-wrap: wrap; gap: 8px; }
.tx-log {
  font-family: var(--font-mono);
  font-size: 13px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px 14px;
  margin: 14px 0;
  min-height: 44px;
}
.tx-log-line { color: var(--text); padding: 1px 0; }
.tx-log-line.muted { color: var(--text-muted); }

/* savepoint code stepper */
#tx-sp-code, #tx-sp-code .tx-codeline { display: block; }
.tx-codeline { padding: 2px 6px; border-radius: 4px; transition: all 0.2s var(--ease); }
.tx-codeline.future { opacity: 0.4; }
.tx-codeline.past { opacity: 0.7; }
.tx-codeline.cur { background: var(--accent-soft, var(--info-soft)); color: var(--text); font-weight: 600; box-shadow: inset 2px 0 0 var(--accent, var(--info)); }

/* deadlock grid */
.tx-dl-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin: 14px 0; }
@media (max-width: 640px) { .tx-dl-grid { grid-template-columns: 1fr; } }
.tx-txn-col {
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 12px 14px;
  background: var(--surface);
}
.tx-txn-col .src-label { margin-bottom: 8px; }

/* ========== ACCESSIBILITY ========== */
@media (prefers-reduced-motion: reduce) {
  * { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
  .progress-fill::after, .lesson-tag::after { animation: none; }
}