body {
      display: flex;
      justify-content: center;
      align-items: center;
      height: 100vh;
      background: #111;
      font-family: Arial, sans-serif;
      color: white;
    }

   .calculator {
  width: 300px;
  padding: 20px;
  background: #222;
  border-radius: 15px;
  box-shadow: 0px 4px 20px rgba(0,0,0,0.5);
}

#display {
  width: 100%;
  height: 150px;          
  font-size: 1.5rem;
  text-align: right;
  padding: 10px;
  border-radius: 8px;
  border: none;
  outline: none;
  background: #fff;
  box-sizing: border-box;
  overflow-y: auto;       
  white-space: pre-line;  
}

    .buttons {
      display: grid;
      grid-template-columns: repeat(4, 60px);
      gap: 10px;
    }

    button {
      height: 60px;
      font-size: 1.2em;
      border: none;
      border-radius: 10px;
      cursor: pointer;
      transition: 0.2s;
    }

    button:hover {
      background: #444;
      color: yellow;
    }