* {
    box-sizing: border-box;
  }

  /* body {
    font-family: 'Segoe UI', sans-serif;
    background: #f0f2f5;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    padding: 10px;
  } */

  .calculator {
    background: #ffffff;
    padding: 20px;
    border-radius: 16px;
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
    width: 100%;
    max-width: 400px;
  }

  .display {
    width: 100%;
    height: 60px;
    background: #000000;
    border-radius: 10px;
    text-align: right;
    padding: 10px;
    font-size: 24px;
    margin-bottom: 20px;
    overflow-x: auto;
    word-break: break-all;
  }

  .buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
  }

  button {
    padding: 20px;
    font-size: 18px;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    transition: background 0.2s ease;
  }

  button:hover {
    background: #dfe6e9;
  }

  .operator {
    background-color: #fab1a0;
  }

  .clear {
    background-color: #ff7675;
  }

  .equal {
    background-color: #55efc4;
    /* grid-column: span 2; */
    
  }

  .zero {
    grid-column: span 2;
  }

  @media (max-width: 480px) {
    .display {
      font-size: 20px;
    }

    button {
      padding: 16px;
      font-size: 16px;
    }
  }