I wrote a simple Fibonacci checker using HTML, CSS, and JS. This is my first JS program, so be sure to tell me everything that is wrong with it. Check it out here (<http://jsfiddle.net/z49fyypt/1/>), and here is the runnable code snippet:

```html
<!DOCTYPE html>
<head>
    <title>Fibonacci checker</title>
    <style>
        body {
            font-family: Algerian, Times, Georgian;
            color: green;
            padding-left: 100px;
        }
    </style>
</head>
<body>
    <h1>Enter a Fibonacci number</h1>
    <input id="InputNum" type="number" required="required" />
    <button onclick="TestFibo()">Test Input</button>
    <h2 id="IsFibo"></h2>

    <script>
        function TestFibo()
        {
            InputNum = document.getElementById("InputNum").value;

            var test1 = Math.sqrt(5 * Math.pow(InputNum, 2) + 4);
            var test2 = Math.sqrt(5 * Math.pow(InputNum, 2) - 4);

            if (test1 == Math.floor(test1) || test2 == Math.floor(test2))
                document.getElementById("IsFibo").innerHTML = InputNum + " is a Fibonacci number";
            else
                document.getElementById("IsFibo").innerHTML = InputNum + " is not a Fibonacci number";
        }
    </script>
</body>
```