/* 
   PDA Simulator — Main Stylesheet
   Palette: Jet Black · Amber Yellow · Pure White
   Font: JetBrains Mono (code) + Inter (UI)
*/

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

:root {
  /* Palette */
  --bg: #0d0d0d;
  --bg2: #131313;
  --bg3: #1a1a1a;
  --border: #2a2a2a;
  --border-hi: #ffd60a;
  --yellow: #ffd60a;
  --yellow-dim: #b89c06;
  --yellow-glow: rgba(255, 214, 10, 0.18);
  --white: #f4f4f4;
  --white-dim: #9a9a9a;
  --green: #39d353;
  --red: #f85149;
  --blue: #58a6ff;
  --purple: #bc8cff;

  /* Typography */
  --font-code: 'JetBrains Mono', monospace;
  --font-ui: 'Inter', sans-serif;

  /* Spacing */
  --r-sm: 6px;
  --r-md: 10px;
  --r-lg: 16px;

  /* Transitions */
  --ease: cubic-bezier(0.4, 0, 0.2, 1);
}

body.light-mode {
  --bg: #f5f5f5;
  --bg2: #ffffff;
  --bg3: #e0e0e0;
  --border: #cccccc;
  --border-hi: #d97706; /* Amber for contrast */
  --yellow: #d97706;
  --yellow-dim: #b89c06;
  --yellow-glow: rgba(217, 119, 6, 0.15);
  --white: #111111;
  --white-dim: #555555;
  --green: #10b981;
  --red: #ef4444;
  --blue: #3b82f6;
  --purple: #8b5cf6;
}

html {
  font-size: 15px;
}

body {
  background: var(--bg);
  color: var(--white);
  font-family: var(--font-ui);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
}

/* ── Scrollbar ── */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

::-webkit-scrollbar-track {
  background: var(--bg2);
}

::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--yellow-dim);
}

/* ══════════ HEADER ══════════ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(13, 13, 13, 0.9);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  max-width: 1600px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 14px;
}

.brand-icon {
  font-size: 2rem;
  color: var(--yellow);
  font-family: var(--font-code);
  line-height: 1;
  text-shadow: 0 0 20px var(--yellow-glow);
}

.brand-title {
  font-family: var(--font-code);
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--yellow);
  letter-spacing: -0.01em;
}

.brand-sub {
  display: block;
  font-size: 0.7rem;
  color: var(--white-dim);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-top: 1px;
}

.tab-nav {
  display: flex;
  gap: 4px;
  align-items: center;
}

.theme-toggle {
  background: transparent;
  border: none;
  font-size: 1.1rem;
  cursor: pointer;
  padding: 6px;
  margin-right: 12px;
  border-radius: 50%;
  transition: all 0.2s var(--ease);
  color: var(--white);
}

.theme-toggle:hover {
  background: var(--border);
  transform: scale(1.1);
}

.tab-btn {
  background: transparent;
  border: 1px solid transparent;
  color: var(--white-dim);
  font-family: var(--font-code);
  font-size: 0.82rem;
  font-weight: 500;
  padding: 7px 18px;
  border-radius: var(--r-sm);
  cursor: pointer;
  transition: all 0.2s var(--ease);
  letter-spacing: 0.02em;
}

.tab-btn:hover {
  color: var(--white);
  border-color: var(--border);
}

.tab-btn.active {
  background: var(--yellow);
  color: #000;
  border-color: var(--yellow);
  font-weight: 700;
  box-shadow: 0 0 18px var(--yellow-glow);
}

/* ══════════ LAYOUT ══════════ */
.main-wrap {
  flex: 1;
  max-width: 1600px;
  margin: 0 auto;
  width: 100%;
  padding: 20px 24px 24px;
}

.tab-panel {
  display: none;
}

.tab-panel.active {
  display: flex;
  gap: 16px;
  min-height: calc(100vh - 130px);
  padding-bottom: 20px;
}

/* ══════════ SIDEBAR CARDS ══════════ */
.sidebar-left,
.sidebar-right {
  width: 280px;
  flex-shrink: 0;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.sidebar-right {
  width: 260px;
  padding-right: 4px;
}

.card {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: 16px;
  transition: border-color 0.2s var(--ease);
}

.card:hover {
  border-color: #333;
}

.card-title {
  font-family: var(--font-code);
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--white);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 14px;
}

.pill {
  background: var(--yellow);
  color: #000;
  font-size: 0.65rem;
  font-weight: 700;
  padding: 2px 7px;
  border-radius: 20px;
}

.divider {
  border: none;
  border-top: 1px solid var(--border);
  margin: 14px 0;
}

/* ── Presets ── */
.preset-list {
  display: flex;
  flex-direction: column;
  gap: 5px;
  margin-bottom: 14px;
}

.preset-btn {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: var(--r-md);
  padding: 8px 10px;
  cursor: pointer;
  transition: all 0.2s var(--ease);
  display: flex;
  flex-direction: row;
  align-items: center;
  gap: 10px;
  color: var(--white);
  text-align: left;
  width: 100%;
}

.preset-btn:hover {
  border-color: var(--yellow-dim);
  background: #1f1f1f;
}

.preset-btn.active {
  border-color: var(--yellow);
  background: rgba(255, 214, 10, 0.07);
  box-shadow: 0 0 14px var(--yellow-glow);
}

.preset-formula {
  font-family: var(--font-code);
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--yellow);
  min-width: 72px;
  flex-shrink: 0;
}

.preset-desc {
  font-size: 0.68rem;
  color: var(--white-dim);
  line-height: 1.3;
}

.preset-divider {
  font-size: 0.62rem;
  color: #444;
  text-align: center;
  letter-spacing: 0.08em;
  padding: 3px 0 1px;
  font-family: var(--font-code);
}

/* ── Input field ── */
.field-label {
  display: block;
  font-size: 0.72rem;
  color: var(--white-dim);
  margin-bottom: 6px;
  letter-spacing: 0.05em;
}

.input-row {
  display: flex;
  gap: 6px;
}

.code-input {
  flex: 1;
  background: var(--bg3);
  border: 1px solid var(--border);
  color: var(--yellow);
  font-family: var(--font-code);
  font-size: 0.95rem;
  padding: 8px 10px;
  border-radius: var(--r-sm);
  outline: none;
  transition: border-color 0.2s;
  letter-spacing: 0.1em;
}

.code-input:focus {
  border-color: var(--yellow);
  box-shadow: 0 0 0 2px var(--yellow-glow);
}

.code-input::placeholder {
  color: #444;
  letter-spacing: 0.04em;
}

.btn-icon {
  background: var(--yellow);
  color: #000;
  border: none;
  border-radius: var(--r-sm);
  font-size: 1rem;
  font-weight: 700;
  width: 36px;
  cursor: pointer;
  transition: all 0.15s;
}

.btn-icon:hover {
  background: #ffe033;
  transform: scale(1.05);
}

.btn-icon:active {
  transform: scale(0.96);
}

.hint-text {
  font-size: 0.7rem;
  margin-top: 5px;
  min-height: 18px;
  color: var(--white-dim);
}

.hint-ok {
  color: var(--green);
}

.hint-err {
  color: var(--red);
}

/* Quick strings */
.quick-strings {
  margin-top: 12px;
}

.qs-label {
  font-size: 0.68rem;
  color: var(--white-dim);
  display: block;
  margin-bottom: 6px;
}

.qs-btns {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
}

.qs-btn {
  background: var(--bg3);
  border: 1px solid var(--border);
  color: var(--yellow);
  font-family: var(--font-code);
  font-size: 0.72rem;
  padding: 3px 9px;
  border-radius: 20px;
  cursor: pointer;
  transition: all 0.15s;
}

.qs-btn:hover {
  border-color: var(--yellow);
  background: rgba(255, 214, 10, 0.08);
}

/* ── Controls ── */
.speed-row {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 12px;
}

.speed-slider {
  flex: 1;
  appearance: none;
  background: var(--border);
  height: 4px;
  border-radius: 2px;
  outline: none;
  cursor: pointer;
}

.speed-slider::-webkit-slider-thumb {
  appearance: none;
  width: 14px;
  height: 14px;
  background: var(--yellow);
  border-radius: 50%;
  box-shadow: 0 0 8px var(--yellow-glow);
}

.speed-val {
  font-family: var(--font-code);
  font-size: 0.72rem;
  color: var(--yellow);
  min-width: 48px;
}

.ctrl-btns {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr 1fr;
  gap: 6px;
  margin-bottom: 6px;
}

.btn {
  padding: 8px 12px;
  border-radius: var(--r-sm);
  font-family: var(--font-code);
  font-size: 0.78rem;
  font-weight: 600;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all 0.15s var(--ease);
  letter-spacing: 0.03em;
}

.btn-primary {
  background: var(--yellow);
  color: #000;
  border-color: var(--yellow);
}

.btn-primary:hover:not(:disabled) {
  background: #ffe033;
  box-shadow: 0 0 20px var(--yellow-glow);
}

.btn-ghost {
  background: transparent;
  color: var(--white);
  border-color: var(--border);
}

.btn-ghost:hover:not(:disabled) {
  border-color: var(--yellow-dim);
  color: var(--yellow);
}

.btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

.btn:active:not(:disabled) {
  transform: scale(0.96);
}

/* Status bar */
.status-bar {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 12px;
  border-radius: var(--r-sm);
  font-family: var(--font-code);
  font-size: 0.72rem;
  border: 1px solid;
  transition: all 0.3s var(--ease);
}

.status-idle {
  background: rgba(154, 154, 154, 0.06);
  border-color: var(--border);
  color: var(--white-dim);
}

.status-running {
  background: rgba(255, 214, 10, 0.08);
  border-color: var(--yellow);
  color: var(--yellow);
  animation: pulse-border 1.5s infinite;
}

.status-accept {
  background: rgba(57, 211, 83, 0.1);
  border-color: var(--green);
  color: var(--green);
}

.status-reject {
  background: rgba(248, 81, 73, 0.1);
  border-color: var(--red);
  color: var(--red);
}

.status-paused {
  background: rgba(88, 166, 255, 0.08);
  border-color: var(--blue);
  color: var(--blue);
}

@keyframes pulse-border {

  0%,
  100% {
    box-shadow: 0 0 0 0 var(--yellow-glow);
  }

  50% {
    box-shadow: 0 0 0 4px var(--yellow-glow);
  }
}

/* Config table */
.config-table {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.config-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 4px 0;
  border-bottom: 1px solid var(--border);
}

.config-row:last-child {
  border-bottom: none;
}

.config-key {
  font-size: 0.7rem;
  color: var(--white-dim);
  font-family: var(--font-code);
}

.config-val {
  font-size: 0.72rem;
  color: var(--yellow);
  font-family: var(--font-code);
  font-weight: 500;
  max-width: 140px;
  text-align: right;
  word-break: break-all;
}

/* ══════════ CENTER VISUALIZATION ══════════ */
.viz-center {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 14px;
  min-width: 0;
}

.viz-block {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  overflow: hidden;
}

.viz-block.expanded {
  position: fixed;
  top: 20px;
  left: 20px;
  right: 20px;
  bottom: 20px;
  z-index: 1000;
  display: flex;
  flex-direction: column;
  box-shadow: 0 0 50px rgba(0,0,0,0.8);
  border-width: 2px;
  border-color: var(--yellow);
}

.viz-block.expanded .canvas-wrap {
  flex: 1;
  height: 100%;
}

.viz-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 16px;
  border-bottom: 1px solid var(--border);
  background: var(--bg3);
}

.viz-label {
  font-family: var(--font-code);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--white-dim);
}

.viz-hint {
  font-size: 0.7rem;
  color: var(--white-dim);
  font-style: italic;
}

.canvas-wrap {
  padding: 12px;
  display: flex;
  justify-content: center;
}

#state-canvas {
  max-width: 100%;
}

/* ── Tape ── */
.tape-stack-row {
  display: flex;
  gap: 14px;
}

.tape-block {
  flex: 1;
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: 14px;
}

.tape-wrap {
  display: flex;
  gap: 3px;
  margin-top: 10px;
  overflow-x: auto;
  padding-bottom: 4px;
  min-height: 54px;
  align-items: center;
}

.tape-cell {
  width: 44px;
  height: 44px;
  flex-shrink: 0;
  background: var(--bg3);
  border: 2px solid var(--border);
  border-radius: var(--r-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-code);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--white);
  transition: all 0.2s var(--ease);
  position: relative;
}

.tape-cell.read {
  color: #555;
  background: #0f0f0f;
  border-color: #222;
  text-decoration: line-through;
}

.tape-cell.current {
  border-color: var(--yellow);
  color: var(--yellow);
  box-shadow: 0 0 16px var(--yellow-glow);
  transform: scale(1.08);
}

.tape-cell.current::after {
  content: '▼';
  position: absolute;
  bottom: -18px;
  font-size: 0.65rem;
  color: var(--yellow);
}

.tape-cell.pending {
  border-color: #333;
  color: #888;
}

/* ── Stack ── */
.stack-block {
  width: 140px;
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: 14px;
  display: flex;
  flex-direction: column;
}

.stack-wrap {
  flex: 1;
  display: flex;
  flex-direction: column;
  margin-top: 10px;
}

.stack-container {
  flex: 1;
  display: flex;
  flex-direction: column-reverse;
  gap: 3px;
  min-height: 100px;
  justify-content: flex-start;
}

.stack-item {
  background: var(--bg3);
  border: 1px solid var(--border);
  font-family: var(--font-code);
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--white);
  padding: 6px 10px;
  border-radius: var(--r-sm);
  text-align: center;
  transition: all 0.25s var(--ease);
  animation: stack-push 0.3s var(--ease);
}

.stack-item.top {
  border-color: var(--yellow);
  color: var(--yellow);
  box-shadow: 0 0 12px var(--yellow-glow);
}

.stack-item.stack-z0 {
  border-color: #333;
  color: var(--white-dim);
  font-style: italic;
}

.stack-bottom {
  font-family: var(--font-code);
  font-size: 0.65rem;
  color: var(--white-dim);
  text-align: center;
  padding-top: 6px;
  border-top: 1px dashed var(--border);
  margin-top: 4px;
}

@keyframes stack-push {
  from {
    opacity: 0;
    transform: scaleX(0.7) translateY(-8px);
  }

  to {
    opacity: 1;
    transform: scaleX(1) translateY(0);
  }
}

.stack-pop {
  animation: stack-pop 0.25s var(--ease) forwards;
}

@keyframes stack-pop {
  from {
    opacity: 1;
    transform: scaleX(1);
  }

  to {
    opacity: 0;
    transform: scaleX(0.5) translateY(-10px);
  }
}

/* Pop flash: red burst when element is removed */
@keyframes flash-red {
  0% {
    border-color: var(--red);
    color: var(--red);
    box-shadow: 0 0 18px rgba(248, 81, 73, 0.7);
    transform: scale(1.05);
  }
  60% {
    border-color: var(--red);
    box-shadow: 0 0 8px rgba(248, 81, 73, 0.3);
  }
  100% {
    opacity: 0;
    transform: scaleX(0.4) translateY(-12px);
  }
}

.stack-item.stack-popping {
  animation: flash-red 0.32s var(--ease) forwards;
  pointer-events: none;
}

/* Push highlight: bright yellow entry */
.stack-item.stack-pushing {
  animation: stack-push 0.3s var(--ease);
  border-color: var(--yellow) !important;
  box-shadow: 0 0 18px var(--yellow-glow) !important;
}

/* ── Phase Indicator Bar ── */
.phase-bar {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 9px 16px;
  background: rgba(255, 214, 10, 0.04);
  border: 1px solid rgba(255, 214, 10, 0.15);
  border-radius: var(--r-md);
  font-family: var(--font-code);
  font-size: 0.75rem;
  color: var(--yellow-dim);
  transition: all 0.3s var(--ease);
  min-height: 38px;
}

.phase-bar.phase-active {
  background: rgba(255, 214, 10, 0.07);
  border-color: rgba(255, 214, 10, 0.35);
  color: var(--yellow);
}

.phase-bar.phase-accept {
  background: rgba(57, 211, 83, 0.07);
  border-color: rgba(57, 211, 83, 0.3);
  color: var(--green);
}

.phase-bar.phase-reject {
  background: rgba(248, 81, 73, 0.07);
  border-color: rgba(248, 81, 73, 0.3);
  color: var(--red);
}

.phase-bar-icon {
  font-size: 0.85rem;
  flex-shrink: 0;
}

.phase-bar-text {
  flex: 1;
}

/* ── Explanation ── */
.explanation-block {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  overflow: hidden;
  transition: border-color 0.3s;
}

.explanation-header {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 16px;
  background: var(--bg3);
  border-bottom: 1px solid var(--border);
}

.exp-icon {
  font-size: 1rem;
  color: var(--yellow);
}

.exp-title {
  font-family: var(--font-code);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  flex: 1;
}

.step-counter {
  font-family: var(--font-code);
  font-size: 0.72rem;
  color: var(--yellow-dim);
  background: rgba(255, 214, 10, 0.1);
  padding: 2px 8px;
  border-radius: 20px;
}

.explanation-body {
  padding: 14px 16px;
  min-height: 60px;
}

.exp-idle {
  color: var(--white-dim);
  font-size: 0.82rem;
  font-style: italic;
}

.exp-step {
  font-size: 0.85rem;
  line-height: 1.6;
}

.exp-step strong {
  color: var(--yellow);
}

.exp-step code {
  background: var(--bg3);
  color: var(--yellow);
  font-family: var(--font-code);
  font-size: 0.82rem;
  padding: 1px 6px;
  border-radius: 4px;
}

.exp-accept {
  color: var(--green);
  font-weight: 600;
}

.exp-reject {
  color: var(--red);
  font-weight: 600;
}

.transition-display {
  border-top: 1px solid var(--border);
  padding: 10px 16px;
  font-family: var(--font-code);
  font-size: 0.82rem;
  color: var(--blue);
  min-height: 36px;
  display: flex;
  align-items: center;
  gap: 8px;
}

/* ══════════ RIGHT SIDEBAR ══════════ */
.log-body {
  max-height: 320px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.log-entry {
  padding: 7px 10px;
  border-radius: var(--r-sm);
  font-family: var(--font-code);
  font-size: 0.72rem;
  border-left: 3px solid var(--border);
  background: var(--bg3);
  color: var(--white-dim);
  transition: all 0.15s;
  cursor: pointer;
}

.log-entry:hover {
  background: #1f1f1f;
}

.log-entry.current {
  border-color: var(--yellow);
  color: var(--yellow);
  background: rgba(255, 214, 10, 0.05);
}

.log-entry.accepted {
  border-color: var(--green);
  color: var(--green);
}

.log-entry.rejected {
  border-color: var(--red);
  color: var(--red);
}

.log-idle {
  color: var(--white-dim);
  font-size: 0.78rem;
  font-style: italic;
}

.log-step-num {
  color: var(--yellow-dim);
  margin-right: 5px;
}

.tuple-display {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.tuple-row {
  display: flex;
  gap: 8px;
  align-items: flex-start;
}

.tuple-sym {
  font-family: var(--font-code);
  font-size: 0.8rem;
  color: var(--yellow);
  font-weight: 700;
  min-width: 28px;
}

.tuple-val {
  font-family: var(--font-code);
  font-size: 0.72rem;
  color: var(--white-dim);
  line-height: 1.5;
}

.tuple-name {
  font-size: 0.65rem;
  color: #555;
  display: block;
}

/* ══════════ LEARN PANEL ══════════ */
.learn-wrap {
  flex: 1;
  max-height: calc(100vh - 130px);
  overflow-y: auto;
  padding-bottom: 40px;
}

.learn-hero {
  text-align: center;
  padding: 48px 20px 36px;
  background: linear-gradient(180deg, rgba(255, 214, 10, 0.05) 0%, transparent 100%);
  border-bottom: 1px solid var(--border);
  margin-bottom: 32px;
}

.learn-hero-badge {
  display: inline-block;
  background: var(--yellow);
  color: #000;
  font-family: var(--font-code);
  font-size: 0.7rem;
  font-weight: 700;
  padding: 3px 12px;
  border-radius: 20px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 16px;
}

.learn-title {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 12px;
}

.learn-subtitle {
  color: var(--white-dim);
  font-size: 1rem;
  max-width: 500px;
  margin: 0 auto;
}

.learn-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 16px;
  padding: 0 20px;
  margin-bottom: 32px;
}

.learn-card {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: 22px;
  transition: border-color 0.2s, transform 0.2s;
}

.learn-card:hover {
  border-color: var(--yellow-dim);
  transform: translateY(-2px);
}

.learn-card-icon {
  font-size: 1.8rem;
  margin-bottom: 12px;
}

.learn-card h3 {
  font-size: 0.95rem;
  font-weight: 700;
  margin-bottom: 10px;
  color: var(--yellow);
}

.learn-card p {
  font-size: 0.85rem;
  color: var(--white-dim);
  line-height: 1.7;
}

.learn-card code {
  background: var(--bg3);
  font-family: var(--font-code);
  font-size: 0.8rem;
  padding: 1px 6px;
  border-radius: 4px;
  color: var(--yellow);
}

.formal-list {
  margin: 10px 0 0 16px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.formal-list li {
  font-size: 0.82rem;
  color: var(--white-dim);
}

.acceptance-chips {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-top: 14px;
}

.chip {
  padding: 4px 12px;
  border-radius: 20px;
  font-family: var(--font-code);
  font-size: 0.72rem;
  font-weight: 600;
}

.chip-accept {
  background: rgba(57, 211, 83, 0.15);
  color: var(--green);
  border: 1px solid rgba(57, 211, 83, 0.3);
}

.chip-or {
  color: var(--white-dim);
  font-size: 0.72rem;
}

.compare-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 10px;
  font-size: 0.78rem;
}

.compare-table th,
.compare-table td {
  padding: 6px 8px;
  border: 1px solid var(--border);
  text-align: center;
}

.compare-table th {
  background: var(--bg3);
  color: var(--yellow);
  font-family: var(--font-code);
}

.compare-table td {
  color: var(--white-dim);
}

.learn-section {
  padding: 0 20px;
  margin-bottom: 28px;
}

.section-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--yellow);
  margin-bottom: 12px;
  border-left: 3px solid var(--yellow);
  padding-left: 12px;
}

.transition-example {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.trans-ex-row {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--r-sm);
  padding: 12px;
  display: grid;
  grid-template-columns: 80px 1fr 1fr;
  gap: 10px;
  align-items: center;
}

.trans-ex-label {
  font-size: 0.7rem;
  color: var(--white-dim);
  font-family: var(--font-code);
}

.trans-ex-code {
  font-family: var(--font-code);
  color: var(--yellow);
  font-size: 0.82rem;
}

.trans-ex-desc {
  font-size: 0.78rem;
  color: var(--white-dim);
}

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

.example-langs.three-col {
  grid-template-columns: repeat(3, 1fr);
}

.example-lang-card {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: 18px;
}

.example-lang-card h4 {
  font-family: var(--font-code);
  font-size: 0.9rem;
  color: var(--yellow);
  margin-bottom: 10px;
}

.example-lang-card p {
  font-size: 0.82rem;
  color: var(--white-dim);
  line-height: 1.65;
}

.example-lang-card code {
  background: var(--bg3);
  font-family: var(--font-code);
  color: var(--yellow);
  font-size: 0.8rem;
  padding: 1px 5px;
  border-radius: 3px;
}

/* ══════════ EDITOR PANEL ══════════ */
.editor-wrap {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 16px;
  padding-bottom: 24px;
}

.editor-header-row {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 20px;
  padding: 4px 0;
}

.editor-title {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.editor-sub {
  font-size: 0.82rem;
  color: var(--white-dim);
}

.editor-actions {
  display: flex;
  gap: 8px;
  flex-shrink: 0;
}

.editor-grid {
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 16px;
  flex: 1;
}

.editor-pane {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

.editor-pane-header {
  padding: 10px 16px;
  background: var(--bg3);
  border-bottom: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--font-code);
  font-size: 0.78rem;
  color: var(--white-dim);
}

.editor-dots {
  display: flex;
  gap: 5px;
}

.editor-dots span {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--border);
}

.editor-dots span:first-child {
  background: #f85149;
}

.editor-dots span:nth-child(2) {
  background: #f0a80b;
}

.editor-dots span:last-child {
  background: #39d353;
}

.json-editor {
  flex: 1;
  background: var(--bg2);
  border: none;
  outline: none;
  resize: none;
  color: var(--white);
  font-family: var(--font-code);
  font-size: 0.82rem;
  padding: 16px;
  line-height: 1.65;
  min-height: 400px;
  tab-size: 2;
}

.editor-status {
  padding: 8px 16px;
  font-family: var(--font-code);
  font-size: 0.72rem;
  border-top: 1px solid var(--border);
}

.editor-status.ok {
  color: var(--green);
}

.editor-status.err {
  color: var(--red);
}

.editor-doc {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: 18px;
  overflow-y: auto;
}

.editor-doc h3 {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--yellow);
  margin-bottom: 12px;
}

.schema-box {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: var(--r-sm);
  padding: 14px;
  font-family: var(--font-code);
  font-size: 0.72rem;
  color: var(--white-dim);
  overflow-x: auto;
  line-height: 1.6;
  margin-bottom: 14px;
  white-space: pre;
}

.doc-note {
  font-size: 0.78rem;
  color: var(--white-dim);
  line-height: 1.6;
}

.doc-note code {
  background: var(--bg3);
  font-family: var(--font-code);
  color: var(--yellow);
  font-size: 0.78rem;
  padding: 1px 5px;
  border-radius: 3px;
}

.doc-note strong {
  color: var(--white);
}

/* ══════════ FOOTER ══════════ */
.site-footer {
  text-align: center;
  padding: 16px 24px;
  font-size: 0.72rem;
  color: var(--white-dim);
  border-top: 1px solid var(--border);
  display: flex;
  justify-content: center;
  gap: 12px;
  align-items: center;
  font-family: var(--font-code);
  letter-spacing: 0.04em;
}

.footer-sep {
  color: var(--border);
}

/* ══════════ ANIMATIONS & EFFECTS ══════════ */
.tab-panel {
  animation: panel-fade 0.25s var(--ease);
}

@keyframes panel-fade {
  from {
    opacity: 0;
    transform: translateY(6px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.glow-accept {
  box-shadow: 0 0 30px rgba(57, 211, 83, 0.3) !important;
  border-color: var(--green) !important;
}

.glow-reject {
  box-shadow: 0 0 30px rgba(248, 81, 73, 0.25) !important;
  border-color: var(--red) !important;
}

/* ══════════ RESPONSIVE ══════════ */
@media (max-width: 1200px) {
  .sidebar-right {
    display: none;
  }
}

@media (max-width: 900px) {
  .tab-panel.active {
    flex-wrap: wrap;
  }

  .sidebar-left {
    width: 100%;
  }

  .tape-stack-row {
    flex-wrap: wrap;
  }

  .stack-block {
    width: 100%;
  }

  .editor-grid {
    grid-template-columns: 1fr;
  }

  .trans-ex-row {
    grid-template-columns: 1fr;
  }

  .example-langs {
    grid-template-columns: 1fr;
  }
}
/* ══════════ STRING BUILDER ══════════ */
.builder-wrap { display: flex; flex-direction: column; gap: 10px; }

.builder-select {
  width: 100%; background: var(--bg3); border: 1px solid var(--border);
  color: var(--yellow); font-family: var(--font-code); font-size: 0.78rem;
  padding: 7px 10px; border-radius: var(--r-sm); outline: none; cursor: pointer;
  transition: border-color 0.2s;
}
.builder-select:focus { border-color: var(--yellow); }

.nm-row { display: flex; gap: 8px; }
.nm-field { flex: 1; }

.nm-input {
  width: 100%; background: var(--bg3); border: 1px solid var(--border);
  color: var(--yellow); font-family: var(--font-code); font-size: 1.1rem;
  font-weight: 700; padding: 8px; border-radius: var(--r-sm); outline: none;
  text-align: center; transition: border-color 0.2s;
}
.nm-input:focus { border-color: var(--yellow); box-shadow: 0 0 0 2px var(--yellow-glow); }
.nm-input::-webkit-inner-spin-button,
.nm-input::-webkit-outer-spin-button { opacity: 0.4; }

.builder-preview {
  font-family: var(--font-code); font-size: 0.76rem; color: var(--white-dim);
  min-height: 20px; padding: 4px 0; letter-spacing: 0.04em;
}

.btn-full { width: 100%; }

.wcwr-mode-row { display: flex; gap: 5px; margin-bottom: 4px; }

.mode-btn {
  flex: 1; background: var(--bg3); border: 1px solid var(--border);
  color: var(--white-dim); font-family: var(--font-code); font-size: 0.7rem;
  padding: 6px 4px; border-radius: var(--r-sm); cursor: pointer; transition: all 0.2s var(--ease);
}
.mode-btn:hover { border-color: var(--yellow-dim); color: var(--white); }
.mode-btn.active { border-color: var(--yellow); color: var(--yellow); background: rgba(255,214,10,0.07); }

/* --- TABLE EDITOR --- */
#panel-table.tab-panel.active { display: block; padding: 20px 24px; }

.te-wrap {
  display: flex; gap: 18px;
  height: calc(100vh - 180px); overflow: hidden;
}

.te-meta-panel {
  width: 310px; flex-shrink: 0;
  display: flex; flex-direction: column; gap: 10px; overflow-y: auto;
}

.te-section-hdr {
  display: flex; align-items: center; gap: 8px;
  font-family: var(--font-code); font-size: 0.72rem; font-weight: 600;
  color: var(--yellow); text-transform: uppercase; letter-spacing: 0.07em; padding-bottom: 2px;
}
.te-section-icon { font-size: 0.85rem; }
.te-meta-fields { display: flex; flex-direction: column; gap: 8px; }
.te-field { display: flex; flex-direction: column; gap: 4px; }

.te-input {
  background: var(--bg3); border: 1px solid var(--border); color: var(--white);
  font-family: var(--font-code); font-size: 0.84rem; padding: 7px 10px;
  border-radius: var(--r-sm); outline: none; transition: border-color 0.2s; width: 100%;
}
.te-input:focus { border-color: var(--yellow); box-shadow: 0 0 0 2px var(--yellow-glow); }
.te-divider { border: none; border-top: 1px solid var(--border); margin: 4px 0; }

.te-paste-hint { font-size: 0.65rem; color: #555; font-family: var(--font-code); margin-bottom: 2px; }

.te-format-box {
  background: var(--bg); border: 1px solid #222; border-radius: var(--r-sm);
  font-family: var(--font-code); font-size: 0.67rem; color: #555;
  padding: 8px 10px; line-height: 1.7; white-space: pre; margin-bottom: 4px; overflow-x: auto;
}

.te-paste-area {
  background: var(--bg3); border: 1px solid var(--border); color: var(--white);
  font-family: var(--font-code); font-size: 0.76rem; padding: 10px;
  border-radius: var(--r-sm); resize: vertical; min-height: 90px;
  outline: none; line-height: 1.7; width: 100%; transition: border-color 0.2s;
}
.te-paste-area:focus { border-color: var(--yellow); }
.te-parse-btn { font-size: 0.75rem; padding: 6px 12px; width: 100%; }
.te-actions { display: flex; flex-direction: column; gap: 6px; }

.te-status { font-family: var(--font-code); font-size: 0.72rem; min-height: 18px; padding: 2px 0; }
.te-status.ok  { color: var(--green); }
.te-status.err { color: var(--red); }

.te-table-panel {
  flex: 1; display: flex; flex-direction: column; gap: 10px;
  overflow: hidden; min-width: 0;
}
.te-table-header-row { display: flex; align-items: flex-start; justify-content: space-between; }
.te-table-title { font-family: var(--font-code); font-size: 0.9rem; font-weight: 700; color: var(--white); margin: 0; }
.te-table-sub { font-size: 0.7rem; color: var(--white-dim); margin-top: 3px; font-family: var(--font-code); }
.te-table-counter {
  font-family: var(--font-code); font-size: 0.72rem; color: var(--yellow-dim);
  background: rgba(255,214,10,0.07); border: 1px solid rgba(255,214,10,0.15);
  padding: 3px 10px; border-radius: 20px; white-space: nowrap;
}

.te-table-scroll {
  flex: 1; overflow: auto;
  border: 1px solid var(--border); border-radius: var(--r-lg);
}
.te-table { width: 100%; border-collapse: collapse; font-family: var(--font-code); font-size: 0.8rem; }
.te-table thead th {
  background: var(--bg3); color: var(--yellow); font-weight: 600;
  padding: 10px; text-align: left; border-bottom: 2px solid var(--border);
  white-space: nowrap; position: sticky; top: 0; z-index: 1;
}
.th-sub { font-weight: 400; color: #555; font-size: 0.65rem; }
.te-table tbody tr { transition: background 0.1s; }
.te-table tbody tr:hover { background: rgba(255,255,255,0.02); }
.te-table td { border-bottom: 1px solid var(--border); padding: 5px 6px; vertical-align: middle; }
.te-num { color: var(--white-dim); text-align: center; font-size: 0.68rem; width: 30px; padding: 5px 8px; }

.te-cell {
  background: transparent; border: 1px solid #1e1e1e; color: var(--white);
  font-family: var(--font-code); font-size: 0.82rem; padding: 6px 8px;
  border-radius: 4px; width: 100%; min-width: 70px; outline: none;
  transition: border-color 0.15s, background 0.15s;
}
.te-cell:focus { border-color: var(--yellow); background: rgba(255,214,10,0.04); }
.te-cell-err { border-color: var(--red) !important; background: rgba(248,81,73,0.05) !important; }

.te-del-btn {
  background: transparent; border: 1px solid #2a2a2a; color: #444;
  width: 26px; height: 26px; border-radius: 4px; cursor: pointer;
  font-size: 0.72rem; transition: all 0.15s;
  display: flex; align-items: center; justify-content: center;
}
.te-del-btn:hover { border-color: var(--red); color: var(--red); background: rgba(248,81,73,0.08); }

.te-add-btn {
  background: transparent; border: 1px dashed var(--border); color: var(--white-dim);
  font-family: var(--font-code); font-size: 0.78rem; padding: 10px;
  border-radius: var(--r-md); cursor: pointer; width: 100%;
  transition: all 0.2s var(--ease); letter-spacing: 0.03em;
}
.te-add-btn:hover { border-color: var(--yellow-dim); color: var(--yellow); background: rgba(255,214,10,0.03); }

.editor-badge {
  font-size: 0.6rem; font-weight: 600; color: #666; background: #1a1a1a;
  border: 1px solid #333; padding: 2px 7px; border-radius: 20px;
  vertical-align: middle; letter-spacing: 0.06em; text-transform: uppercase; margin-left: 6px;
}

@media (max-width: 900px) {
  .te-wrap { flex-direction: column; height: auto; overflow: visible; }
  .te-meta-panel { width: 100%; }
}

/* ── Controls: full-width Reset ── */
.ctrl-reset-btn {
  grid-column: 1 / -1; /* full width */
}

/* ── Transition Functions Card ── */
.tfn-body {
  display: flex;
  flex-direction: column;
  gap: 3px;
  max-height: 200px;
  overflow-y: auto;
}

.tfn-row {
  font-family: var(--font-code);
  font-size: 0.72rem;
  padding: 5px 8px;
  border-radius: var(--r-sm);
  border-left: 3px solid var(--border);
  background: var(--bg3);
  color: var(--white-dim);
  transition: all 0.15s;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.tfn-row.tfn-active {
  border-left-color: var(--yellow);
  color: var(--yellow);
  background: rgba(255, 214, 10, 0.07);
  box-shadow: 0 0 8px rgba(255, 214, 10, 0.1);
}

/* ── Table Editor: Epsilon Insert Button ── */
.te-eps-btn {
  background: transparent;
  border: 1px solid rgba(255, 214, 10, 0.3);
  color: var(--yellow-dim);
  font-family: var(--font-code);
  font-size: 0.72rem;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 20px;
  cursor: pointer;
  transition: all 0.2s var(--ease);
  white-space: nowrap;
  letter-spacing: 0.03em;
}

.te-eps-btn:hover {
  background: rgba(255, 214, 10, 0.1);
  border-color: var(--yellow);
  color: var(--yellow);
  box-shadow: 0 0 10px rgba(255, 214, 10, 0.15);
}

/* ── Learn Panel: Acceptance Methods ── */
.acceptance-card {
  position: relative;
  padding-top: 44px !important;
}

.acceptance-card-badge {
  position: absolute;
  top: 14px;
  left: 18px;
  font-family: var(--font-code);
  font-size: 0.62rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 3px 10px;
  border-radius: 20px;
}

.badge-final {
  background: rgba(57, 211, 83, 0.15);
  color: var(--green);
  border: 1px solid rgba(57, 211, 83, 0.3);
}

.badge-empty {
  background: rgba(88, 166, 255, 0.15);
  color: var(--blue);
  border: 1px solid rgba(88, 166, 255, 0.3);
}

.acceptance-formula {
  background: var(--bg);
  border: 1px solid var(--border);
  border-left: 3px solid var(--yellow);
  border-radius: var(--r-sm);
  padding: 8px 12px;
  font-family: var(--font-code);
  font-size: 0.78rem;
  color: var(--yellow);
  margin: 8px 0;
  overflow-x: auto;
  white-space: nowrap;
}

.acceptance-example-box {
  background: rgba(255, 214, 10, 0.04);
  border: 1px solid rgba(255, 214, 10, 0.15);
  border-radius: var(--r-md);
  padding: 12px;
  margin-top: 14px;
}

.aex-label {
  font-family: var(--font-code);
  font-size: 0.68rem;
  color: var(--yellow-dim);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 10px;
}

.aex-steps {
  display: flex;
  flex-direction: column;
  gap: 5px;
}

.aex-step {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  font-size: 0.8rem;
  color: var(--white-dim);
}

.aex-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 22px;
  height: 22px;
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: 50%;
  font-family: var(--font-code);
  font-size: 0.68rem;
  font-weight: 700;
  color: var(--white-dim);
  flex-shrink: 0;
}

.aex-step.aex-accept {
  color: var(--green);
}

.aex-step.aex-accept .aex-num {
  background: rgba(57, 211, 83, 0.15);
  border-color: rgba(57, 211, 83, 0.4);
  color: var(--green);
}

.acceptance-comparison {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: 18px;
  margin-top: 16px;
}

.acceptance-comparison-title {
  font-family: var(--font-code);
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--yellow);
  margin-bottom: 12px;
}