* {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }

    body {
      font-family: Arial, sans-serif;
      background-color: #f2f2f2;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100vh;
    }

    h1 {
      margin-bottom: 20px;
      text-ansform: uppercase;
      color: #333;
    }

    .calculator {
      background-color: #fff;
      padding: 30px;
      border-radius: 15px;
      box-shadow: 0 0 10px rgba(0,0,0,0.1);
      text-align: center;
    }

    #display {
      width: 100%;
      height: 50px;
      font-size: 24px;
      text-align: right;
      margin-bottom: 20px;
      padding: 10px;
      /* border: 1px solid #ccc; */
      /* border-radius: 8px; */
    }

    .buttons {
      display: grid;
      grid-template-columns: repeat(4, 60px);
      grid-gap: 15px;
      justify-content: center;
    }

    .buttons button {
      height: 60px;
      font-size: 20px;
      border: none;
      border-radius: 10px;
      background-color: #e0f7fa;
      cursor: pointer;
      ansition: background-color 0.3s ease;
    }

    .buttons button:hover {
      background-color: #b2ebf2;
    }