/* ============================================================
   NOT Gate Virtual Laboratory — Style Sheet
   Virtual Instrumentation Labs Interactive Learning Platform
   ============================================================ */

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

:root {
  /* Laboratory Colour Palette */
  --lab-bg:           #ffffff;
  --panel-bg:         #f4f5f7;
  --panel-border:     #d0d4da;
  --header-bg:        #1a2744;
  --header-text:      #ffffff;
  --accent:           #2563eb;
  --accent-light:     #dbeafe;
  --text-primary:     #1e293b;
  --text-secondary:   #475569;
  --text-muted:       #94a3b8;
  --success:          #16a34a;
  --danger:           #dc2626;
  --wire-off:         #9ca3af;
  --wire-on:          #22c55e;
  --led-off:          #6b7280;
  --led-on:           #22c55e;
  --led-glow:         rgba(34, 197, 94, 0.5);
  --switch-track-off: #cbd5e1;
  --switch-track-on:  #22c55e;
  --switch-knob:      #ffffff;
  --gate-fill:        #e8ecf1;
  --gate-stroke:      #1a2744;
  --shadow-sm:        0 1px 3px rgba(0,0,0,0.08);
  --shadow-md:        0 4px 12px rgba(0,0,0,0.10);
  --radius:           6px;
  --radius-lg:        10px;
  --font-sans:        'Segoe UI', 'Inter', -apple-system, sans-serif;
  --font-mono:        'Cascadia Code', 'Fira Mono', 'Consolas', monospace;
}

html { font-size: 15px; }

body {
  font-family: var(--font-sans);
  background: var(--lab-bg);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
}

/* ── Laboratory Title Bar ──────────────────────────────────── */
.lab-title-bar {
  background: var(--header-bg);
  color: var(--header-text);
  padding: 14px 28px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 8px rgba(0,0,0,0.18);
}

.lab-title-bar h1 {
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: 0.3px;
}

.lab-title-bar .lab-subtitle {
  font-size: 0.78rem;
  color: #94a3b8;
  font-weight: 400;
}

.lab-badge {
  background: var(--accent);
  color: #fff;
  font-size: 0.68rem;
  padding: 3px 10px;
  border-radius: 12px;
  font-weight: 600;
  letter-spacing: 0.5px;
  text-transform: uppercase;
}

/* ── Module Navigation Bar ─────────────────────────────────── */
.gate-nav-bar {
  background: #0f172a;
  border-bottom: 1px solid #1e293b;
  padding: 8px 24px;
  position: sticky;
  top: 57px;
  z-index: 99;
}

.gate-nav-container {
  max-width: 1440px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 8px;
  overflow-x: auto;
  scrollbar-width: thin;
}

.gate-nav-label {
  color: #64748b;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-right: 8px;
  white-space: nowrap;
}

.gate-nav-link {
  color: #94a3b8;
  text-decoration: none;
  font-size: 0.82rem;
  font-weight: 500;
  padding: 5px 14px;
  border-radius: 6px;
  white-space: nowrap;
  transition: all 0.2s ease;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.gate-nav-link:hover {
  color: #ffffff;
  background: rgba(37, 99, 235, 0.2);
  border-color: rgba(37, 99, 235, 0.4);
}

.gate-nav-link.active {
  color: #ffffff;
  background: #2563eb;
  border-color: #3b82f6;
  font-weight: 600;
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.4);
}

/* ── Main Layout ───────────────────────────────────────────── */
.lab-main {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 20px;
  padding: 20px 24px;
  max-width: 1440px;
  margin: 0 auto;
}

/* ── Panel Component ───────────────────────────────────────── */
.lab-panel {
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.lab-panel__header {
  background: var(--header-bg);
  color: var(--header-text);
  padding: 10px 18px;
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.4px;
  text-transform: uppercase;
  display: flex;
  align-items: center;
  gap: 8px;
}

.lab-panel__header .icon {
  font-size: 1rem;
}

.lab-panel__body {
  padding: 18px;
}

/* ── SVG Circuit Canvas ────────────────────────────────────── */
.circuit-canvas {
  width: 100%;
  background: #ffffff;
  border-radius: var(--radius);
  border: 1px solid var(--panel-border);
}

.circuit-canvas svg {
  width: 100%;
  height: auto;
  display: block;
}

/* SVG Text */
.svg-label {
  font-family: var(--font-sans);
  font-size: 13px;
  font-weight: 600;
  fill: var(--text-primary);
}

.svg-label-small {
  font-family: var(--font-sans);
  font-size: 11px;
  fill: var(--text-secondary);
}

.svg-value {
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: 700;
}

/* Wires */
.wire {
  stroke: var(--wire-off);
  stroke-width: 3;
  fill: none;
  stroke-linecap: round;
  stroke-linejoin: round;
  transition: stroke 0.3s ease;
}

.wire.active {
  stroke: var(--wire-on);
  filter: drop-shadow(0 0 4px var(--led-glow));
}

/* Signal Pulse */
.signal-pulse {
  r: 5;
  fill: var(--wire-on);
  opacity: 0;
  filter: drop-shadow(0 0 6px var(--led-glow));
}

.signal-pulse.animate {
  opacity: 1;
}

/* Gate Body */
.gate-body {
  fill: var(--gate-fill);
  stroke: var(--gate-stroke);
  stroke-width: 2.5;
  transition: fill 0.3s ease;
}

.gate-body.active {
  fill: #d1fae5;
  stroke: var(--success);
}

.gate-label-text {
  font-family: var(--font-sans);
  font-size: 15px;
  font-weight: 700;
  fill: var(--header-bg);
  text-anchor: middle;
  pointer-events: none;
}

/* LED */
.led-body {
  transition: fill 0.3s ease;
}

.led-body.off {
  fill: var(--led-off);
}

.led-body.on {
  fill: var(--led-on);
  filter: drop-shadow(0 0 10px var(--led-glow)) drop-shadow(0 0 20px var(--led-glow));
}

/* SVG Toggle Switch */
.svg-switch-track {
  rx: 12;
  ry: 12;
  fill: var(--switch-track-off);
  cursor: pointer;
  transition: fill 0.3s ease;
}

.svg-switch-track.on {
  fill: var(--switch-track-on);
}

.svg-switch-knob {
  fill: var(--switch-knob);
  filter: drop-shadow(0 1px 3px rgba(0,0,0,0.2));
  cursor: pointer;
  transition: cx 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ── Control Panel Toggle Switches ─────────────────────────── */
.toggle-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 0;
  border-bottom: 1px solid var(--panel-border);
}

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

.toggle-label {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text-primary);
}

.toggle-wrapper {
  display: flex;
  align-items: center;
  gap: 10px;
}

.toggle-state {
  font-size: 0.75rem;
  font-weight: 700;
  font-family: var(--font-mono);
  min-width: 28px;
  text-align: center;
  color: var(--text-muted);
  transition: color 0.3s;
}

.toggle-state.on {
  color: var(--success);
}

.toggle-switch {
  position: relative;
  width: 48px;
  height: 26px;
  cursor: pointer;
}

.toggle-switch input {
  opacity: 0;
  width: 0;
  height: 0;
}

.toggle-track {
  position: absolute;
  inset: 0;
  background: var(--switch-track-off);
  border-radius: 26px;
  transition: background 0.3s ease;
}

.toggle-switch input:checked + .toggle-track {
  background: var(--switch-track-on);
}

.toggle-track::after {
  content: '';
  position: absolute;
  top: 3px;
  left: 3px;
  width: 20px;
  height: 20px;
  background: var(--switch-knob);
  border-radius: 50%;
  box-shadow: 0 1px 4px rgba(0,0,0,0.2);
  transition: transform 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

.toggle-switch input:checked + .toggle-track::after {
  transform: translateX(22px);
}

/* ── Live Display ──────────────────────────────────────────── */
.live-display {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-top: 12px;
}

.live-cell {
  background: #ffffff;
  border: 1px solid var(--panel-border);
  border-radius: var(--radius);
  padding: 10px;
  text-align: center;
}

.live-cell__label {
  font-size: 0.7rem;
  text-transform: uppercase;
  font-weight: 600;
  letter-spacing: 0.5px;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.live-cell__value {
  font-family: var(--font-mono);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
  transition: color 0.3s;
}

.live-cell__value.high {
  color: var(--success);
}

.live-cell__value.low {
  color: var(--danger);
}

/* ── Boolean Expression Display ────────────────────────────── */
.bool-expr {
  background: #ffffff;
  border: 1px solid var(--panel-border);
  border-radius: var(--radius);
  padding: 14px;
  margin-top: 12px;
  text-align: center;
}

.bool-expr__formula {
  font-family: var(--font-mono);
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--header-bg);
  margin-bottom: 6px;
}

.bool-expr__calc {
  font-family: var(--font-mono);
  font-size: 0.88rem;
  color: var(--text-secondary);
  min-height: 1.3em;
}

/* ── Logic State Indicator ─────────────────────────────────── */
.logic-state {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  margin-top: 12px;
  padding: 10px;
  border-radius: var(--radius);
  font-weight: 700;
  font-size: 0.88rem;
  transition: background 0.3s, color 0.3s;
}

.logic-state.low {
  background: #fef2f2;
  color: var(--danger);
  border: 1px solid #fecaca;
}

.logic-state.high {
  background: #f0fdf4;
  color: var(--success);
  border: 1px solid #bbf7d0;
}

.logic-state__dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  transition: background 0.3s, box-shadow 0.3s;
}

.logic-state.low .logic-state__dot {
  background: var(--danger);
}

.logic-state.high .logic-state__dot {
  background: var(--success);
  box-shadow: 0 0 8px var(--led-glow);
}

/* ── Buttons ───────────────────────────────────────────────── */
.btn-group {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 14px;
}

.btn {
  font-family: var(--font-sans);
  font-size: 0.78rem;
  font-weight: 600;
  padding: 8px 16px;
  border: 1px solid var(--panel-border);
  border-radius: var(--radius);
  cursor: pointer;
  background: #ffffff;
  color: var(--text-primary);
  transition: background 0.2s, border-color 0.2s, transform 0.1s;
}

.btn:hover {
  background: var(--accent-light);
  border-color: var(--accent);
}

.btn:active {
  transform: scale(0.97);
}

.btn--primary {
  background: var(--accent);
  color: #ffffff;
  border-color: var(--accent);
}

.btn--primary:hover {
  background: #1d4ed8;
}

.btn--danger {
  color: var(--danger);
  border-color: #fecaca;
}

.btn--danger:hover {
  background: #fef2f2;
}

/* ── Bottom Section ────────────────────────────────────────── */
.lab-bottom {
  grid-column: 1 / -1;
}

/* Tab Navigation */
.tab-nav {
  display: flex;
  gap: 0;
  border-bottom: 2px solid var(--panel-border);
  margin-bottom: 0;
}

.tab-btn {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 600;
  padding: 10px 20px;
  background: transparent;
  border: none;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  cursor: pointer;
  color: var(--text-muted);
  transition: color 0.2s, border-color 0.2s;
}

.tab-btn:hover {
  color: var(--text-primary);
}

.tab-btn.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

.tab-content {
  display: none;
  padding: 18px 0;
}

.tab-content.active {
  display: block;
}

/* ── Truth Table ───────────────────────────────────────────── */
.truth-table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--font-mono);
  font-size: 0.88rem;
}

.truth-table th {
  background: var(--header-bg);
  color: var(--header-text);
  padding: 10px 20px;
  text-align: center;
  font-weight: 600;
  letter-spacing: 0.3px;
}

.truth-table td {
  padding: 10px 20px;
  text-align: center;
  border-bottom: 1px solid var(--panel-border);
  transition: background 0.3s;
}

.truth-table tr.highlight {
  background: var(--accent-light);
  font-weight: 700;
}

.truth-table tr.highlight td {
  color: var(--accent);
  border-color: #93c5fd;
}

/* ── Observation / Working Principle Text ──────────────────── */
.info-section {
  margin-bottom: 16px;
}

.info-section h3 {
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--header-bg);
  margin-bottom: 6px;
  border-left: 3px solid var(--accent);
  padding-left: 10px;
}

.info-section p,
.info-section li {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.65;
}

.info-section ul {
  list-style: disc;
  padding-left: 22px;
  margin-top: 4px;
}

/* ── Application Demo ──────────────────────────────────────── */
.app-demo {
  display: flex;
  align-items: center;
  gap: 20px;
  flex-wrap: wrap;
}

.app-demo__circuit {
  flex: 1;
  min-width: 280px;
}

.app-demo__desc {
  flex: 1;
  min-width: 220px;
}

.lamp-status {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  border-radius: var(--radius);
  font-weight: 700;
  font-size: 0.85rem;
  margin-top: 8px;
  transition: background 0.3s, color 0.3s;
}

.lamp-status.off {
  background: #fef2f2;
  color: var(--danger);
  border: 1px solid #fecaca;
}

.lamp-status.on {
  background: #f0fdf4;
  color: var(--success);
  border: 1px solid #bbf7d0;
}

/* ── Quiz Mode ─────────────────────────────────────────────── */
.quiz-question {
  background: #ffffff;
  border: 1px solid var(--panel-border);
  border-radius: var(--radius);
  padding: 18px;
  margin-bottom: 14px;
}

.quiz-question__text {
  font-size: 0.92rem;
  font-weight: 600;
  margin-bottom: 12px;
  color: var(--text-primary);
}

.quiz-options {
  display: flex;
  gap: 10px;
}

.quiz-opt {
  flex: 1;
  padding: 10px;
  text-align: center;
  font-family: var(--font-mono);
  font-size: 1.1rem;
  font-weight: 700;
  border: 2px solid var(--panel-border);
  border-radius: var(--radius);
  background: #ffffff;
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s, transform 0.1s;
}

.quiz-opt:hover {
  border-color: var(--accent);
  background: var(--accent-light);
}

.quiz-opt:active {
  transform: scale(0.96);
}

.quiz-opt.correct {
  border-color: var(--success);
  background: #f0fdf4;
  color: var(--success);
}

.quiz-opt.incorrect {
  border-color: var(--danger);
  background: #fef2f2;
  color: var(--danger);
}

.quiz-feedback {
  margin-top: 10px;
  padding: 10px 14px;
  border-radius: var(--radius);
  font-size: 0.85rem;
  font-weight: 600;
  display: none;
}

.quiz-feedback.correct {
  display: block;
  background: #f0fdf4;
  color: var(--success);
  border: 1px solid #bbf7d0;
}

.quiz-feedback.incorrect {
  display: block;
  background: #fef2f2;
  color: var(--danger);
  border: 1px solid #fecaca;
}

.quiz-score {
  font-size: 0.82rem;
  color: var(--text-secondary);
  margin-bottom: 12px;
}

/* ── Keyframe Animations ───────────────────────────────────── */
@keyframes pulseGlow {
  0%, 100% { opacity: 0.7; }
  50%      { opacity: 1; }
}

@keyframes signalMove {
  0%   { offset-distance: 0%; opacity: 1; }
  100% { offset-distance: 100%; opacity: 1; }
}

.wire.active {
  animation: pulseGlow 1.5s ease-in-out infinite;
}

/* ── Responsive Design Rules ──────────────────────────────── */

/* Mobile Portrait (stacked vertical: simulator top, controls/panels below) */
@media (max-width: 767px) and (orientation: portrait) {
  html { font-size: 14px; }

  .lab-title-bar {
    padding: 10px 16px;
    flex-direction: column;
    align-items: flex-start;
    gap: 6px;
  }

  .gate-nav-bar {
    top: auto;
    padding: 6px 12px;
  }

  .lab-main {
    grid-template-columns: 1fr !important;
    padding: 12px;
    gap: 16px;
  }

  .circuit-canvas {
    width: 100%;
    overflow-x: auto;
  }

  .circuit-canvas svg {
    width: 100%;
    height: auto;
    max-height: 280px;
  }

  .live-display {
    grid-template-columns: 1fr;
  }

  .app-demo {
    flex-direction: column;
  }

  .btn, .quiz-opt {
    min-height: 44px;
    padding: 12px 16px;
  }
}

/* Mobile Landscape (wide side-by-side: simulator left, panel right) */
@media (max-height: 500px) and (orientation: landscape) {
  html { font-size: 13px; }

  .lab-title-bar {
    padding: 8px 16px;
  }

  .gate-nav-bar {
    padding: 4px 12px;
  }

  .lab-main {
    grid-template-columns: 1.1fr 0.9fr !important;
    padding: 10px 14px;
    gap: 12px;
  }

  .circuit-canvas svg {
    width: 100%;
    height: auto;
    max-height: 240px;
  }

  .btn, .quiz-opt {
    min-height: 40px;
  }
}

/* Tablet (scaled layout with preserved proportions) */
@media (min-width: 768px) and (max-width: 1024px) {
  .lab-main {
    grid-template-columns: 1.1fr 0.9fr;
    padding: 16px;
    gap: 16px;
  }

  .circuit-canvas svg {
    width: 100%;
    height: auto;
  }
}