body {
      font-family: sans-serif;
      display: flex;
      justify-content: center;
      align-items: center;
      height: 100vh;
      background: linear-gradient(to bottom, #0a0a1a, #2a1a4a);
      margin: 0;
    }

    .calculator {
      background-color: #2a2a4a;
      border-radius: 15px;
      box-shadow: 0 4px 8px rgba(0, 0, 0, 0.3);
      padding: 20px;
      width: 300px;
      z-index: 1;
    }

    .display {
      margin-bottom: 20px;
    }

    .display input {
      width: 100%;
      padding: 15px;
      font-size: 24px;
      text-align: right;
      border: none;
      background-color: #3a3a5a;
      color: #fff;
      border-radius: 8px;
      box-sizing: border-box;
    }

    .buttons {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      grid-gap: 10px;
    }

    .buttons button {
      padding: 15px;
      font-size: 20px;
      border: none;
      background-color: #4a4a6a;
      color: #fff;
      border-radius: 8px;
      cursor: pointer;
      transition: background-color 0.3s ease;
    }

    .buttons button:hover {
      background-color: #5a5a7a;
    }

    .buttons button:active {
      background-color: #6a6a8a;
    }