* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Arial, sans-serif;
  background: #121212;
  color: white;
  display: flex;
  justify-content: center;
  padding: 20px;
}

.container {
  width: 100%;
  max-width: 900px;
}

h1 {
  text-align: center;
}

textarea {
  width: 100%;
  height: 180px;
  padding: 12px;
  border-radius: 10px;
  border: none;
  margin-bottom: 16px;
  font-size: 16px;
}

.controls {
  display: flex;
  gap: 10px;
  margin-bottom: 20px;
}

button {
  padding: 12px 20px;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  font-size: 16px;
  background: #4caf50;
  color: white;
}

button:hover {
  opacity: 0.9;
}

.board {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 10px;
}

.cell {
  aspect-ratio: 1 / 1;
  background: #1f1f1f;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 10px;
  cursor: pointer;
  user-select: none;
  transition: 0.2s;
  font-size: 14px;
}

.cell:hover {
  transform: scale(1.02);
}

.marked {
  background: #4caf50;
  color: white;
  text-decoration: line-through;
}

.free {
  background: #2196f3;
}