* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background: #fff;
  color: #111;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  -webkit-tap-highlight-color: transparent;
  touch-action: none;
}

#app {
  position: relative;
  width: 100vw;
  height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

canvas#ruler {
  display: block;
  touch-action: none;
  cursor: grab;
}

canvas#ruler:active {
  cursor: grabbing;
}

/* Readout panel */
#readout {
  position: absolute;
  top: 8px;
  left: 8px;
  background: rgba(255, 255, 255, 0.92);
  border: 1px solid #ccc;
  border-radius: 8px;
  padding: 8px 12px;
  font-size: 13px;
  max-width: 220px;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  z-index: 10;
}

.readout-title {
  font-weight: 600;
  color: #999;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 4px;
}

#readout-values {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.readout-row {
  display: flex;
  justify-content: space-between;
  gap: 12px;
}

.readout-label {
  font-weight: 600;
}

.readout-value {
  color: #555;
  font-variant-numeric: tabular-nums;
}

/* Controls */
#controls {
  position: absolute;
  top: 8px;
  right: 8px;
  display: flex;
  gap: 8px;
  z-index: 10;
}

#controls button {
  background: rgba(255, 255, 255, 0.92);
  border: 1px solid #ccc;
  border-radius: 8px;
  color: #111;
  padding: 8px 14px;
  font-size: 14px;
  cursor: pointer;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

#controls button:hover {
  background: rgba(240, 240, 240, 0.95);
}

#controls button:active {
  background: rgba(230, 230, 230, 0.98);
}

/* Configuration panel */
#panel {
  position: absolute;
  top: 0;
  right: 0;
  width: 340px;
  max-width: 90vw;
  height: 100vh;
  background: rgba(255, 255, 255, 0.98);
  border-left: 1px solid #ccc;
  overflow-y: auto;
  padding: 16px;
  z-index: 20;
  transition: transform 0.25s ease;
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

#panel.hidden {
  transform: translateX(100%);
  pointer-events: none;
}

.panel-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
}

.panel-header h2 {
  font-size: 16px;
  font-weight: 600;
}

.panel-header button {
  background: none;
  border: none;
  color: #999;
  font-size: 18px;
  cursor: pointer;
  padding: 4px 8px;
}

.panel-header button:hover {
  color: #111;
}

.panel-section {
  margin-bottom: 20px;
}

.panel-section h3 {
  font-size: 13px;
  font-weight: 600;
  color: #999;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 8px;
}

/* Circle list */
.circle-item {
  background: rgba(0, 0, 0, 0.03);
  border: 1px solid #ddd;
  border-radius: 6px;
  padding: 8px;
  margin-bottom: 6px;
  font-size: 13px;
}

.circle-item-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 4px;
}

/* Primary buttons */
#add-ring,
#add-scale,
.io-buttons button {
  background: #4a6fa5;
  border: none;
  border-radius: 4px;
  color: #fff;
  padding: 6px 12px;
  font-size: 13px;
  cursor: pointer;
}

#add-ring:hover,
#add-scale:hover,
.io-buttons button:hover {
  background: #5a7fb5;
}

#add-ring {
  margin-bottom: 8px;
}

.circle-item-controls {
  display: flex;
  align-items: center;
  gap: 8px;
}

.circle-item-remove {
  background: none;
  border: none;
  color: #999;
  cursor: pointer;
}

.circle-item-remove:hover {
  color: #111;
}

.ring-slots {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-top: 6px;
}

.ring-slot {
  display: flex;
  align-items: center;
  gap: 6px;
}

.ring-slot-label {
  width: 42px;
  color: #999;
  font-size: 12px;
}

.ring-slot .dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
}

.display-controls {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: #555;
}

.display-controls input[type="range"] {
  flex: 1;
  max-width: 150px;
}

.display-controls span {
  min-width: 30px;
  text-align: right;
  font-variant-numeric: tabular-nums;
}

.ring-slot-select {
  flex: 1;
  background: rgba(0, 0, 0, 0.03);
  border: 1px solid #ddd;
  border-radius: 4px;
  color: #111;
  padding: 4px 6px;
  font-size: 13px;
}

.toggle-switch {
  position: relative;
  width: 36px;
  height: 20px;
  background: #ccc;
  border-radius: 10px;
  cursor: pointer;
  transition: background 0.2s;
}

.toggle-switch.active {
  background: #4a6fa5;
}

.toggle-switch::after {
  content: '';
  position: absolute;
  top: 2px;
  left: 2px;
  width: 16px;
  height: 16px;
  background: #fff;
  border-radius: 50%;
  transition: transform 0.2s;
}

.toggle-switch.active::after {
  transform: translateX(16px);
}

/* Scale editor */
.scale-form {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-bottom: 8px;
}

.scale-form input[type="text"],
.scale-form input[type="number"] {
  background: rgba(0, 0, 0, 0.03);
  border: 1px solid #ddd;
  border-radius: 4px;
  color: #111;
  padding: 6px 8px;
  font-size: 13px;
  width: 100%;
}

.scale-form input:focus {
  border-color: #4a6fa5;
  outline: none;
}

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

.scale-form-row input {
  flex: 1;
}

/* Scale list */
#scale-list {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.scale-item {
  display: flex;
  align-items: center;
  gap: 8px;
  background: rgba(0, 0, 0, 0.03);
  border: 1px solid #ddd;
  border-radius: 4px;
  padding: 4px 8px;
  font-size: 12px;
}

.scale-item .dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  flex-shrink: 0;
}

.scale-item .name {
  font-weight: 600;
  flex: 1;
}

.scale-item .formula {
  color: #999;
  font-size: 11px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  max-width: 140px;
}

.scale-item button {
  background: none;
  border: none;
  color: #999;
  cursor: pointer;
  font-size: 14px;
  padding: 2px 4px;
}

.scale-item button:hover {
  color: #111;
}

.scale-item.error {
  border-color: #c33;
}

.scale-item.error .name {
  color: #c33;
}

/* Import/Export */
.io-buttons {
  display: flex;
  gap: 6px;
  margin-bottom: 6px;
}

.io-buttons button {
  flex: 1;
}

#io-textarea {
  width: 100%;
  background: rgba(0, 0, 0, 0.03);
  border: 1px solid #ddd;
  border-radius: 4px;
  color: #111;
  padding: 6px 8px;
  font-size: 12px;
  font-family: monospace;
  resize: vertical;
}

#io-textarea:focus {
  border-color: #4a6fa5;
  outline: none;
}

/* Responsive */
@media (max-width: 600px) {
  #readout {
    font-size: 11px;
    max-width: 160px;
    padding: 6px 8px;
  }
  #panel {
    width: 100vw;
  }
}