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

body {
  font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background: #f0f0f5;
  color: #1a1a2e;
  min-height: 100vh;
  overflow-x: hidden;
}

.app-header {
  background: #ffffff;
  border-bottom: 1px solid #d0d0e0;
  padding: 16px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.app-header-left {
  display: flex;
  align-items: center;
  gap: 12px;
}

.app-header h1 {
  margin: 0px;
  font-size: 20px;
  font-weight: 700;
  background-color: var(--color-active);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.app-header .subtitle {
  font-size: 13px;
  color: #6b6b80;
}

.shift-hint {
  display: flex;
  align-items: center;
  gap: 10px;
  background: rgba(255, 165, 0, 0.08);
  border: 1px solid rgba(255, 165, 0, 0.2);
  border-radius: 10px;
  padding: 8px 18px;
  font-size: 13px;
  color: #c78700;
  font-weight: 500;
}

.shift-hint kbd {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: #e8e8f0;
  border: 1px solid #c0c0d0;
  border-bottom-width: 3px;
  border-radius: 5px;
  padding: 2px 10px;
  font-family: inherit;
  font-size: 12px;
  font-weight: 700;
  color: #c78700;
  min-width: 28px;
}

.shift-hint-icon {
  font-size: 18px;
}

.main-layout {
  display: flex;
  height: calc(100vh - 61px);
}

.sidebar {
  width: 250px;
  background: #ffffff;
  border-right: 1px solid #d0d0e0;
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  overflow-y: auto;
}

.panel {
  background: #f5f5fa;
  border: 1px solid #d0d0e0;
  border-radius: 10px;
  padding: 14px;
}

.panel-title {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1.2px;
  color: #6b6b80;
  margin-bottom: 10px;
}

.color-picker-wrap {
  display: flex;
  align-items: center;
  gap: 10px;
}

.color-swatch {
  width: 40px;
  height: 40px;
  border-radius: 8px;
  border: 2px solid #c0c0d0;
  cursor: pointer;
  position: relative;
  flex-shrink: 0;
}

.color-swatch input[type="color"] {
  position: absolute;
  top: -10px;
  left: -10px;
  width: 60px;
  height: 60px;
  border: none;
  cursor: pointer;
  opacity: 0;
}

.color-hex {
  font-family: 'Consolas', 'Monaco', monospace;
  font-size: 14px;
  color: #4a4a60;
  background: #e8e8f0;
  border: 1px solid #c0c0d0;
  border-radius: 6px;
  padding: 8px 10px;
  width: 100px;
  text-align: center;
  outline: none;
}

.preset-colors {
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  gap: 4px;
  margin-top: 8px;
}

.preset-color {
  width: 100%;
  aspect-ratio: 1;
  border-radius: 4px;
  border: 1px solid #c0c0d0;
  cursor: pointer;
  transition: transform 0.1s, border-color 0.15s;
}

.preset-color:hover {
  transform: scale(1.25);
  border-color: var(--color-active);;
}

.brush-size-row {
  display: flex;
  align-items: center;
  gap: 10px;
}

.brush-size-slider {
  flex: 1;
  -webkit-appearance: none;
  appearance: none;
  height: 6px;
  border-radius: 3px;
  background: #d0d0e0;
  outline: none;
}

.brush-size-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--color-active);;
  cursor: pointer;
  border: 2px solid #fff;
}

.brush-size-slider::-moz-range-thumb {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--color-active);;
  cursor: pointer;
  border: 2px solid #fff;
}

.brush-size-value {
  font-size: 14px;
  font-weight: 600;
  color: var(--color-active);;
  min-width: 32px;
  text-align: center;
}

.toggle-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 5px 0;
}

.toggle-label {
  font-size: 13px;
  color: #4a4a60;
}

.toggle-switch {
  position: relative;
  width: 42px;
  height: 22px;
  cursor: pointer;
  flex-shrink: 0;
}

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

.toggle-slider {
  position: absolute;
  top: 0; left: 0; right: 0; bottom: 0;
  background: #c0c0d0;
  border-radius: 11px;
  transition: 0.25s;
}

.toggle-slider::before {
  content: '';
  position: absolute;
  width: 16px;
  height: 16px;
  left: 3px;
  top: 3px;
  background: #fff;
  border-radius: 50%;
  transition: 0.25s;
}

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

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

.btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 16px;
  border-radius: 8px;
  border: 1px solid #c0c0d0;
  background: #f5f5fa;
  color: #1a1a2e;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  width: 100%;
  font-family: inherit;
}

.btn:hover {
  background: #e8e8f0;
  border-color: #a0a0b8;
}

.btn-primary {
  background: var(--color-active);;
  border-color: var(--color-active);;
  color: #fff;
}

.btn-primary:hover {
  background: #5a52e0;
}

.btn-danger {
  background: #fff0f0;
  border-color: #d0a0a0;
  color: #cc3333;
}

.btn-danger:hover {
  background: #ffe0e0;
}

.canvas-area {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 24px;
  background: #f0f0f5;
  position: relative;
}

.canvas-wrapper {
  position: relative;
  border: 2px solid #c0c0d0;
  border-radius: 12px;
  overflow: hidden;
  background: #f5f5fa;
  box-shadow: 0 8px 32px rgba(0,0,0,0.08);
}

#strokesCanvas {
  display: block;
  cursor: none;
}

#gridCanvas {
  position: absolute;
  top: 0;
  left: 0;
  pointer-events: none;
  z-index: 5;
}

#cursorOverlay {
  position: absolute;
  top: 0;
  left: 0;
  pointer-events: none;
  z-index: 10;
}

.shift-indicator {
  position: absolute;
  top: 10px;
  left: 50%;
  transform: translateX(-50%);
  background: rgba(108, 99, 255, 0.92);
  color: #fff;
  padding: 4px 14px;
  border-radius: 6px;
  font-size: 11px;
  font-weight: 600;
  display: none;
  z-index: 20;
  pointer-events: none;
  white-space: nowrap;
}

.shift-indicator.visible { display: block; }

.line-mode-indicator {
  position: absolute;
  top: 36px;
  left: 50%;
  transform: translateX(-50%);
  background: rgba(255, 165, 0, 0.92);
  color: #fff;
  padding: 4px 14px;
  border-radius: 6px;
  font-size: 11px;
  font-weight: 600;
  display: none;
  z-index: 20;
  pointer-events: none;
  white-space: nowrap;
}

.line-mode-indicator.visible { display: block; }

.preview-section {
  position: absolute;
  right: 24px;
  top: 50%;
  transform: translateY(-50%);
  display: flex;
  flex-direction: column;
  gap: 28px;
  padding: 24px;
  background: #ffffff;
  border: 1px solid #d0d0e0;
  border-radius: 14px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.06);
}

.preview-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
}

.preview-label {
  font-size: 11px;
  color: #6b6b80;
  font-weight: 600;
}

.preview-canvas {
  border: 1px solid #d0d0e0;
  border-radius: 6px;
  image-rendering: auto;
}

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

.actions-row .btn { flex: 1; }

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

.tool-btn {
  flex: 1;
  padding: 8px;
  border-radius: 6px;
  border: 1px solid #c0c0d0;
  background: #f5f5fa;
  color: #4a4a60;
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s;
  text-align: center;
  font-family: inherit;
}

.tool-btn.active {
  background: var(--color-active);;
  border-color: var(--color-active);;
  color: #fff;
}

.tool-btn:hover:not(.active) {
  background: #e8e8f0;
}

.line-width-display {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-top: 6px;
}

.line-preview {
  flex: 1;
  height: 28px;
  background: #e8e8f0;
  border-radius: 4px;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.line-preview-dot {
  border-radius: 50%;
  background: var(--color-active);;
}

.checker-bg {
  background-image:
    linear-gradient(45deg, #e0e0ea 25%, transparent 25%),
    linear-gradient(-45deg, #e0e0ea 25%, transparent 25%),
    linear-gradient(45deg, transparent 75%, #e0e0ea 75%),
    linear-gradient(-45deg, transparent 75%, #e0e0ea 75%);
  background-size: 16px 16px;
  background-position: 0 0, 0 8px, 8px -8px, -8px 0px;
  background-color: #eaeaf2;
}