body {
  font-family: sans-serif;
  display: flex;
  flex-direction: column;
  align-items: center;
  background: #f5f5f5;
  margin: 0;
}
.grid {
  display: grid;
  grid-template-columns: repeat(30, 1fr);
  width: 90vmin;
  height: 90vmin;
  max-width: 90vw;
  max-height: 90vw;
  gap: 1px;
}
.cell {
  width: 100%;
  aspect-ratio: 1 / 1;
  background: #fff;
  border: 1px solid #ccc;
  cursor: pointer;
}
.toolbar {
  margin: 10px 0;
  display: flex;
  align-items: center;
  gap: 10px;
}
#colorPicker {
  width: 40px;
  height: 40px;
  padding: 0;
  border: none;
  background: none;
}
button {
  padding: 10px 16px;
  font-size: 14px;
  cursor: pointer;
}