:root {
  --bg: #f6f7fb;
  --bg-muted: #e9ebf3;
  --text: #1f2630;
  --primary: #4a6cf7;
  --border: #cfd5e4;
  --accent: #f0f4ff;
  --surface: #ffffff;
  --muted: #6b7280;

  /* Vaporwave Palette */
  --vw-orange: #FF5E00;
  --vw-fuchsia: #FF00FF;
  --vw-blue: #00FFFF;
  --vw-purple: #8A2BE2;
}

body.dark {
  --bg: #111827;
  --bg-muted: #1f2937;
  --text: #ffffff;
  --primary: #8b9cf9;
  --border: #374151;
  --accent: #1f2937;
  --surface: #0b1221;
}

.header-left {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.back-link {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  text-decoration: none;
  color: var(--muted);
  font-weight: 600;
  font-size: 0.875rem;
  transition: color 0.2s;
}

.back-link:hover {
  color: var(--primary);
}

.header-actions {
  display: flex;
  flex-direction: row;
  gap: 0.5rem;
  align-items: center;
}

.toolbar {
  background-color: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 0.75rem 1rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  position: sticky;
  top: 0;
  z-index: 10;
}

.mode-selector {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.mode-btn {
  background-color: var(--bg);
  border: 1px solid var(--border);
  padding: 0.4rem 0.875rem;
  border-radius: 0.5rem;
  cursor: pointer;
  font-weight: 600;
  color: var(--text);
  font-size: 0.875rem;
  transition: all 0.2s;
}

.mode-btn:hover {
  border-color: var(--primary);
}

.mode-btn.active {
  background-color: var(--primary);
  color: white;
  border-color: var(--primary);
}

.workspace {
  display: flex;
  flex-direction: row;
  padding: 1rem 0;
  gap: 1rem;
  align-items: stretch;
  background-color: var(--bg);
  min-height: 500px;
}

.panel {
  flex: 1;
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: 0.75rem;
  padding: 1rem;
  display: flex;
  flex-direction: column;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
  overflow: auto;
}

div#leftPanel {
    min-width: 425px;
    overflow: hidden;
}

.tutorial-step {
  margin-top: 1.5rem;
  background-color: var(--bg);
  padding: 1rem;
  border-radius: 0.5rem;
  font-size: 0.875rem;
  line-height: 1.6;
}

/* Decoder Symbol & Circuit */
.decoder-container {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100%;
  position: relative;
}

.decoder-block {
  border: 4px solid var(--border);
  background-color: var(--bg);
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  padding: 20px 0;
  box-sizing: border-box;
  z-index: 2;
}

.decoder-title {
  text-align: center;
  font-weight: bold;
  font-size: 1.2rem;
  color: var(--text);
  margin-top: -10px;
}

/* Pins */
.pin {
  display: flex;
  align-items: center;
  gap: 10px;
}

.pin-label {
  font-weight: bold;
  color: var(--muted);
  width: 20px;
  text-align: center;
}

/* Toggles & LEDs */
.toggle-btn {
  width: 40px;
  height: 40px;
  border-radius: 5px;
  border: 2px solid var(--border);
  background-color: var(--surface);
  color: var(--text);
  font-weight: bold;
  font-size: 1.2rem;
  cursor: pointer;
  transition: all 0.2s;
}

.toggle-btn.active {
  background-color: var(--primary);
  color: white;
  border-color: var(--primary);
}

.led {
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background-color: #333; /* Off state */
  border: 2px solid var(--border);
  transition: background-color 0.2s;
}

.led.on {
  background-color: var(--vw-blue); /* Neon Blue */
  border-color: var(--vw-blue);
}

/* Active Low Indicator (Bubble) */
.bubble {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  border: 2px solid var(--border);
  background-color: var(--surface);
  position: absolute;
  bottom: -16px;
  left: 50%;
  transform: translateX(-50%);
}

/* SVG Circuit Overlay */
.circuit-overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 1;
}

/* Truth Table */
.truth-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 1rem;
  text-align: center;
}

.truth-table th, .truth-table td {
  border: 1px solid var(--border);
  padding: 8px;
  color: var(--text);
}

.truth-table th {
  background-color: var(--bg);
  font-weight: bold;
}

.truth-table tr.active-row {
  background-color: rgba(255, 94, 0, 0.2);
  border: 2px solid var(--vw-orange);
}

/* Challenge Mode Layout */
.challenge-container {
  display: flex;
  flex-direction: column;
  gap: 20px;
  align-items: center;
  width: 100%;
}

.decoders-row {
  display: flex;
  justify-content: space-around;
  width: 100%;
  gap: 20px;
}

.decoder-block.challenge {
  border: 2px solid var(--vw-purple) !important;
}

.or-gate-container {
  margin-top: 20px;
  display: flex;
  flex-direction: column;
  align-items: center;
  position: relative;
  width: 100%;
}

.target-function-display {
  font-size: 1.5rem;
  font-weight: bold;
  color: var(--vw-fuchsia);
  margin-bottom: 1rem;
}

/* Dropdown Selectors */
.select-input {
  background-color: var(--surface);
  border: 2px solid var(--border);
  color: var(--text);
  border-radius: 4px;
  padding: 2px 5px;
  font-weight: bold;
  cursor: pointer;
  font-size: 0.8rem;
  outline: none;
}

.select-input:focus {
  border-color: var(--primary);
}

/* OR Gate SVG Classes */
.or-gate-svg {
  filter: none;
}

/* Logic Match Highlighting */
.match-neon {
  background-color: rgba(255, 94, 0, 0.4) !important;
  border: 2px solid var(--vw-orange) !important;
}

.hidden {
  display: none !important;
}

/* SVG Signal Classes */
.signal-path {
  stroke-width: 3;
  fill: none;
  transition: stroke 0.2s, stroke-opacity 0.2s;
}

.signal-dot {
  transition: fill 0.2s;
}

/* S1 Signals (Purple) */
.signal-s1 { stroke: rgba(138, 43, 226, 0.3); }
.signal-s1.high { stroke: var(--vw-purple); }
.signal-s1-fill { fill: rgba(138, 43, 226, 0.3); }
.signal-s1-fill.high { fill: var(--vw-purple); }

/* S1 NOT Signals (Purple) */
.signal-ns1 { stroke: rgba(138, 43, 226, 0.3); }
.signal-ns1.high { stroke: var(--vw-purple); }
.signal-ns1-fill { fill: rgba(138, 43, 226, 0.3); }
.signal-ns1-fill.high { fill: var(--vw-purple); }

/* S0 Signals (Blue) */
.signal-s0 { stroke: rgba(0, 255, 255, 0.3); }
.signal-s0.high { stroke: var(--vw-blue); }
.signal-s0-fill { fill: rgba(0, 255, 255, 0.3); }
.signal-s0-fill.high { fill: var(--vw-blue); }

/* S0 NOT Signals (Blue) */
.signal-ns0 { stroke: rgba(0, 255, 255, 0.3); }
.signal-ns0.high { stroke: var(--vw-blue); }
.signal-ns0-fill { fill: rgba(0, 255, 255, 0.3); }
.signal-ns0-fill.high { fill: var(--vw-blue); }

/* Enable Signals (Orange) */
.signal-e { stroke: var(--border); }
.signal-e.high { stroke: var(--vw-orange); }
.signal-e-fill { fill: var(--border); }
.signal-e-fill.high { fill: var(--vw-orange); }

/* Output Signals (Cyan/Neon Blue) */
.signal-out { stroke: var(--border); }
.signal-out.high { stroke: var(--vw-blue); }

/* Gate Classes */
.signal-gate0, .signal-gate1, .signal-gate2, .signal-gate3 {
  stroke: var(--border);
}
.signal-gate0.high, .signal-gate1.high, .signal-gate2.high, .signal-gate3.high {
  stroke: var(--vw-blue);
}

/* Inverter Bubble Styling */
.inverter-bubble {
  fill: var(--surface);
  transition: fill 0.2s, stroke 0.2s;
}

/* Modal Dialogs */
.dialog-backdrop {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.5);
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 100;
}

.dialog {
  background-color: var(--surface);
  padding: 2rem;
  border-radius: 1rem;
  max-width: 500px;
  width: 90%;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
}

.dialog h2 {
  margin-top: 0;
  margin-bottom: 1.5rem;
}

.dialog-actions {
  display: flex;
  justify-content: flex-end;
  margin-top: 2rem;
}

button.primary {
  background-color: var(--primary);
  color: white;
  border: none;
  padding: 0.6rem 1.2rem;
  border-radius: 0.5rem;
  font-weight: 600;
  cursor: pointer;
  transition: background-color 0.2s;
}

button.primary:hover {
  background-color: #3a5bd9;
}

.form-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
}

/* Switch UI */
.switch {
  position: relative;
  display: inline-block;
  width: 50px;
  height: 24px;
}

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

.slider {
  position: absolute;
  cursor: pointer;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: var(--bg-muted);
  transition: .4s;
  border: 1px solid var(--border);
}

.slider:before {
  position: absolute;
  content: "";
  height: 16px;
  width: 16px;
  left: 4px;
  bottom: 3px;
  background-color: white;
  transition: .4s;
}

input:checked + .slider {
  background-color: var(--primary);
}

input:checked + .slider:before {
  transform: translateX(26px);
}

.slider.round {
  border-radius: 24px;
}

.slider.round:before {
  border-radius: 50%;
}