body {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
  background: #222;
  font-family: Arial, sans-serif;
  color: #eee;
  flex-direction: column;
}

h1 {
  margin-bottom: 10px;
}

#out {
  background: #333;
  padding: 10px;
  margin-bottom: 15px;
  font-size: 24px;
  border-radius: 4px;
  width: 320px;
  text-align: right;
}

.container {
  display: flex;
  justify-content: center;
  gap: 15px;
}


.number {
  display: grid;
  grid-template-columns: repeat(3, 60px);
  grid-gap: 10px;
}


.opet {
  display: flex;
  flex-direction: column;
  gap: 10px;
}


button {
  width: 60px;
  height: 60px;
  font-size: 24px;
  border: none;
  border-radius: 6px;
  background: #555;
  color: white;
  cursor: pointer;
}

button:hover {
  background: #777;
}