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

:root {
  --bg: #ffffff;
  --fg: #000000;
  --border: #d0d0d0;
  --border-hover: #a0a0a0;
  --border-active: #000000;
  --panel-bg: #fafafa;
  --hover-bg: #f0f0f0;
  --active-bg: #e8e8e8;
  --radius: 4px;
}

body {
  font-family: 'SF Mono', 'Monaco', 'Inconsolata', 'Roboto Mono', 'Courier New', monospace;
  background: var(--bg);
  color: var(--fg);
  font-size: 13px;
  line-height: 1.5;
}

.container {
  max-width: 1600px;
  margin: 0 auto;
}

/* Header */
.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 24px;
  border-bottom: 1px solid var(--border);
  gap: 20px;
}

.header-left {
  display: flex;
  align-items: center;
  gap: 20px;
}

.back-link {
  font-size: 14px;
  color: #666;
  text-decoration: none;
  transition: color 0.15s ease;
}

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

.header h1 {
  font-size: 16px;
  font-weight: 500;
  letter-spacing: -0.3px;
}

.header-actions {
  display: flex;
  gap: 8px;
}

/* Buttons */
.btn {
  padding: 8px 16px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--fg);
  cursor: pointer;
  font-family: inherit;
  font-size: 12px;
  border-radius: var(--radius);
  transition: all 0.15s ease;
}

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

.btn:active {
  background: var(--active-bg);
}

.btn-secondary {
  background: var(--panel-bg);
}

.btn-block {
  width: 100%;
  margin-top: 8px;
}

/* Main Layout */
.main {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 1px;
  background: var(--border);
  min-height: calc(100vh - 61px);
}

/* Panels */
.sidebar, .editor {
  background: var(--bg);
  padding: 20px 16px;
}

.panel {
  margin-bottom: 20px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--border);
}

.panel:last-child {
  border-bottom: none;
  margin-bottom: 0;
  padding-bottom: 0;
}

.panel h2 {
  font-size: 12px;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 12px;
  color: #666;
}

/* Form Elements */
.select {
  width: 100%;
  padding: 8px 12px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--fg);
  font-family: inherit;
  font-size: 13px;
  border-radius: var(--radius);
  margin-bottom: 8px;
}

.select:focus {
  outline: none;
  border-color: var(--border-active);
}

/* Editor */
.editor {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 32px 24px;
}

.canvas-container {
  width: 100%;
  max-width: 800px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg);
}

#editorCanvas {
  width: 100%;
  height: 100%;
  display: block;
  cursor: pointer;
}

/* Grid Controls */
.grid-controls {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.control-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.control-row label {
  font-size: 12px;
  color: #666;
}

.stepper {
  display: flex;
  align-items: center;
  gap: 8px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 4px;
  background: var(--bg);
}

.btn-stepper {
  width: 28px;
  height: 28px;
  border: none;
  background: var(--panel-bg);
  color: var(--fg);
  cursor: pointer;
  font-size: 16px;
  border-radius: 3px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.15s ease;
  font-family: inherit;
}

.btn-stepper:hover {
  background: var(--hover-bg);
}

.btn-stepper:active {
  background: var(--active-bg);
}

.stepper span {
  min-width: 20px;
  text-align: center;
  font-size: 13px;
  font-weight: 500;
}

.cell-controls {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.hint {
  font-size: 12px;
  color: #999;
  line-height: 1.4;
}

/* Context Menu */
.context-menu {
  position: fixed;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  z-index: 1000;
  padding: 4px;
  min-width: 200px;
}

.context-menu-content {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 4px;
}

.context-menu-item {
  aspect-ratio: 1;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.15s ease;
  padding: 8px;
}

.context-menu-item:hover {
  background: var(--hover-bg);
  border-color: var(--border-hover);
}

.context-menu-item canvas {
  width: 100%;
  height: 100%;
}

/* Responsive */
@media (max-width: 768px) {
  .main {
    grid-template-columns: 1fr;
  }
  
  .header {
    flex-direction: column;
    align-items: stretch;
  }
  
  .header-left {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }
  
  .header-actions {
    width: 100%;
    justify-content: stretch;
  }
  
  .header-actions .btn {
    flex: 1;
  }
}

/* Toggle Switch */
.toggle-switch {
  position: relative;
  display: inline-block;
  width: 40px;
  height: 20px;
}

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

.toggle-slider {
  position: absolute;
  cursor: pointer;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: var(--panel-bg);
  border: 1px solid var(--border);
  border-radius: 20px;
  transition: 0.3s;
}

.toggle-slider:before {
  position: absolute;
  content: "";
  height: 14px;
  width: 14px;
  left: 2px;
  bottom: 2px;
  background-color: var(--fg);
  border-radius: 50%;
  transition: 0.3s;
}

.toggle-switch input:checked + .toggle-slider {
  background-color: var(--active-bg);
  border-color: var(--border-active);
}

.toggle-switch input:checked + .toggle-slider:before {
  transform: translateX(20px);
}

/* Color Input */
.color-input {
  width: 60px;
  height: 32px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  cursor: pointer;
  padding: 2px;
  background: var(--bg);
}

.color-input::-webkit-color-swatch-wrapper {
  padding: 0;
}

.color-input::-webkit-color-swatch {
  border: none;
  border-radius: 3px;
}

.color-input::-moz-color-swatch {
  border: none;
  border-radius: 3px;
}
/* ── Brush shape graphical picker ── */
.shape-picker {
  display: flex;
  gap: 4px;
  align-items: center;
}

.shape-btn {
  width: 28px;
  height: 28px;
  padding: 4px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--fg);
  cursor: pointer;
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  transition: background 0.1s, border-color 0.1s, color 0.1s;
}

.shape-btn:hover {
  background: var(--hover-bg);
  border-color: var(--border-hover);
}

.shape-btn.active {
  background: var(--fg);
  color: var(--bg);
  border-color: var(--fg);
}

.shape-btn svg {
  width: 100%;
  height: 100%;
  display: block;
}