:root {
  --bg: #f6f7fb;
  --bg-muted: #e9ebf3;
  --text: #1f2630;
  --primary: #4a6cf7;
  --border: #cfd5e4;
  --accent: #f0f4ff;
  --surface: #ffffff;
  --kmap-cell-size: 50px;
  --kmap-border: #334155;
  --active-color: var(--primary);
  --inactive-opacity: 0.1;
}

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;
}

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

.difficulty-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;
}

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

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

.workspace {
  display: flex;
  flex-direction: column;
  padding: 1rem;
  gap: 1rem;
  align-items: center;
  background-color: var(--bg);
}

.top-row-layout {
  display: flex;
  width: 100%;
  max-width: 1000px;
  justify-content: space-between;
  align-items: flex-start;
  gap: 2rem;
  margin-bottom: 1rem;
}

.instructional-container {
  flex: 1;
  display: flex;
  justify-content: left;
  align-items: flex-start;
  padding-top: 1rem;
}

.speech-bubble {
  position: relative;
  background: var(--surface);
  border: 3px solid var(--primary);
  border-radius: 1.25rem;
  padding: 1.25rem;
  box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
  width: 100%;
  max-width: 320px;
  min-height: 80px;
  transition: all 0.3s ease;
}

.speech-bubble::before {
  content: '';
  position: absolute;
  left: -12px;
  top: 40px;
  width: 0;
  height: 0;
  border-top: 12px solid transparent;
  border-bottom: 12px solid transparent;
  border-right: 12px solid var(--primary);
}

.speech-bubble::after {
  content: '';
  position: absolute;
  left: -8px;
  top: 40px;
  width: 0;
  height: 0;
  border-top: 12px solid transparent;
  border-bottom: 12px solid transparent;
  border-right: 12px solid var(--surface);
}

#instructionText {
  margin: 0;
  font-size: 1rem;
  line-height: 1.5;
  font-weight: 600;
  color: var(--text);
}

.bubble-controls {
  margin-top: 1rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  justify-content: center;
  max-width: 200px;
  margin-left: auto;
  margin-right: auto;
}

.bubble-btn {
  padding: 0.4rem 0.8rem;
  border-radius: 0.5rem;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text);
  font-weight: 700;
  cursor: pointer;
  font-size: 0.875rem;
  transition: all 0.2s;
}

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

.bubble-btn.undo {
  border-color: #ef4444;
  color: #ef4444;
}

.bubble-btn.undo:hover {
  background: #fef2f2;
}

.kmap-container {
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: 0.75rem;
  padding: 1rem 2rem;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

.kmap-grid-wrapper {
  position: relative;
  display: inline-block;
  width: 250px;
  height: 150px;
  margin-bottom: 1.5rem;
}

.kmap-grid-collection {
  display: grid;
  gap: 1rem;
}

.kmap-submap {
  background: var(--surface);
}

.kmap-table {
  border-collapse: collapse;
  table-layout: fixed;
  width: 250px;
  height: 150px;
}

.kmap-table th {
  background-color: var(--accent);
  border: 1px solid var(--border);
  text-align: center;
  padding: 0;
  width: var(--kmap-cell-size);
  height: var(--kmap-cell-size);
  transition: opacity 0.2s ease;
}

.kmap-table th.inactive .kmap-gray-code,
.kmap-table th.inactive .kmap-corner-label {
  opacity: var(--inactive-opacity);
}

.kmap-table td {
  border: 1px solid var(--border);
  text-align: center;
  padding: 0;
  width: var(--kmap-cell-size);
  height: var(--kmap-cell-size);
  background-color: transparent;
}

.kmap-cell-input {
  width: 100%;
  height: 100%;
  border: none;
  background: transparent;
  text-align: center;
  font-size: 1.5rem;
  font-weight: 300;
  color: var(--text);
  cursor: pointer;
  outline: none;
  transition: all 0.2s ease;
}

.kmap-cell-input.inactive {
  opacity: var(--inactive-opacity);
  background-color: var(--bg-muted);
}

.kmap-gray-code {
  display: inline-block;
  font-size: 1rem;
  font-weight: 700;
  color: var(--text);
}

.kmap-corner-label {
  position: relative;
  min-width: var(--kmap-cell-size);
  min-height: var(--kmap-cell-size);
  display: grid;
  place-items: center;
  color: var(--text);
  font-weight: 700;
  overflow: hidden;
}

.kmap-corner-label .kmap-diagonal {
  position: absolute;
  inset: 0;
}

.kmap-corner-label .kmap-diagonal::before {
  content: "";
  position: absolute;
  top: 50%;
  left: -20%;
  width: 140%;
  border-top: 1px solid var(--border);
  transform: rotate(45deg);
  transform-origin: center;
}

.kmap-corner-label .kmap-variable-block {
  position: relative;
  z-index: 1;
  display: flex;
  gap: 0.2rem;
  font-size: 0.85rem;
}

.kmap-corner-label .kmap-vars-row {
  position: absolute;
  bottom: 0.5rem;
  left: 0.5rem;
}

.kmap-corner-label .kmap-vars-col {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
}

.symmetry-overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 10;
}

.symmetry-selector {
  position: absolute;
  background: transparent;
  cursor: pointer;
  z-index: 15;
  pointer-events: auto;
  transition: background-color 0.2s;
}

.symmetry-selector.hover-active {
  background-color: rgba(74, 108, 247, 0.3);
}

.wavy-line {
  fill: none;
  stroke-width: 4;
  stroke-linecap: round;
  filter: drop-shadow(0 2px 4px rgba(0,0,0,0.1));
}

.kmap-input-controls {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  justify-content: center;
  align-items: center;
}

.kmap-input-row {
  display: flex;
  gap: 0.5rem;
}

.mux-input-btn {
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: 0.25rem;
  width: 2.5rem;
  height: 2.5rem;
  font-weight: bold;
  cursor: pointer;
  color: var(--text);
  transition: all 0.2s;
  display: flex;
  justify-content: center;
  align-items: center;
}

.mux-input-btn:hover {
  background-color: var(--accent);
  border-color: var(--primary);
}

.mux-container {
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: 1rem;
  padding: 1rem;
  width: 100%;
  box-sizing: border-box;
}

.mux-container h3 {
  margin: 0 0 1.5rem 0;
  text-align: center;
}

.mux-diagram {
  min-height: 300px;
  width: 100%;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  border: 2px dashed var(--border);
  border-radius: 0.5rem;
  color: var(--muted);
  text-align: center;
  padding: 1.5rem;
  box-sizing: border-box;
}

.mux-diagram p {
  margin: 0;
}

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

.tutorial-step p {
  margin: 0.5rem 0;
}