According To My Calculations Calculator

<!DOCTYPE html>
<html>
<head>
  <title>Calculator By Goldnera</title>
  <link rel="stylesheet" type="text/css" href="style.css">
</head>
<body>
  <div class="calculator">
    <input type="text" id="result" readonly>
    <div class="keypad">
      <button onclick="clearResult()">C</button>
      <button onclick="appendToResult('/')">/</button>
      <button onclick="appendToResult('7')">7</button>
      <button onclick="appendToResult('8')">8</button>
      <button onclick="appendToResult('9')">9</button>
      <button onclick="appendToResult('*')">*</button>
      <button onclick="appendToResult('4')">4</button>
      <button onclick="appendToResult('5')">5</button>
      <button onclick="appendToResult('6')">6</button>
      <button onclick="appendToResult('-')">-</button>
      <button onclick="appendToResult('1')">1</button>
      <button onclick="appendToResult('2')">2</button>
      <button onclick="appendToResult('3')">3</button>
      <button onclick="appendToResult('+')">+</button>
      <button onclick="appendToResult('0')">0</button>
      <button onclick="calculateResult()">=</button>
    </div>
  </div>

  <script src="script.js"></script>
</body>
</html>
<style>.calculator {
    width: 300px;
    margin: 0 auto;
    background-color: #f2f2f2;
    border-radius: 8px;
    box-shadow: 0px 0px 10px rgba(0, 0, 0, 0.1);
    padding: 20px;
  }

  input {
    width: 100%;
    height: 50px;
    font-size: 24px;
    padding: 10px;
    border: none;
    border-radius: 4px;
    margin-bottom: 20px;
  }

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

  button {
    width: 100%;
    height: 60px;
    font-size: 24px;
    border: none;
    border-radius: 4px;
    background-color: #e0e0e0;
    color: #333333;
    cursor: pointer;
    transition: background-color 0.3s ease;
  }

  button:hover {
    background-color: #cccccc;
  }

  .clear {
    grid-column: 1 / span 2;
  }

  .zero {
    grid-column: 1 / span 2;
  }

  </style>
  <script>function clearResult() { // To Open his file, save it and open it
    document.getElementById("result").value = "";
  }

  function appendToResult(value) {
    document.getElementById("result").value += value;
  }

  function calculateResult() {
    var result = document.getElementById("result").value;
    var calculatedResult = eval(result);
    document.getElementById("result").value = calculatedResult;
  }
  </script>