body {
  margin: 0;
  padding: 20px;
  font-family: Inter, system-ui, Arial, sans-serif;
  background: #f5f7fb;
}

.app {
  max-width: 860px;
  margin: 0 auto;
  display: grid;
  gap: 12px;
}

.toolbar {
  display: flex;
  gap: 8px;
  align-items: center;
  flex-wrap: wrap;
}

button, input[type="range"] {
  padding: 6px 10px;
}

button.active {
  font-weight: 700;
  border: 2px solid #111;
}

.canvas-wrap {
  border: 1px solid #d8deea;
  border-radius: 10px;
  background: #fff;
  overflow: hidden;
}

canvas {
  display: block;
  width: 100%;
  height: 460px;
  touch-action: none;
  cursor: crosshair;
}