@media (max-width: 768px) {
  .calculator {
    margin-left: 5%;
    margin-top: 15%;
    max-width: 90%;
  }

  .calculator h1 {
    font-size: 40px;
  }

  .input-box {
    flex-direction: column;
    align-items: stretch;
    padding: 25px;
  }

  .input-box input {
    margin-right: 0;
    margin-bottom: 15px;
    font-size: 16px;
  }

  .input-box button {
    width: 100%;
    padding: 12px;
  }

  #result {
    font-size: 18px;
  }
}

@media (max-width: 480px) {
  .calculator {
    margin-left: 20px;
    margin-top: 20%;
    text-align: center;
  }

  .calculator h1 {
    font-size: 28px;
  }

  .input-box {
    padding: 20px;
  }

  .input-box input {
    font-size: 14px;
    padding: 12px;
  }

  .input-box button {
    font-size: 14px;
    padding: 10px;
  }

  #result {
    font-size: 16px;
  }
}

@media (max-width: 1200px) {
  .calculator {
    margin-left: auto;
    margin-right: auto;
    margin-top: 8%;
  }
}