index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="./style.css">
    <link href='https://fonts.googleapis.com/css?family=Orbitron' rel='stylesheet' type='text/css'>
    <script src="index.js" defer></script>
    <title>Calculator</title>
</head>
<body>
    <div class="calculator-body">
        <div class="display">
            0
        </div>
        <div class="pad">
            <div class="btn">
                <div class="top-row">
                    <div class="key ac">AC</div>
                    <div class="key p-m">+/-</div>
                    <div class="key percent">%</div>
                    <div class="operator divide">/</div>
                </div>
                <div class="789-row">
                    <div class="key seven">7</div>
                    <div class="key eight">8</div>
                    <div class="key nine">9</div>
                    <div class="operator multiply">*</div>
                </div>
                <div class="456-row">
                    <div class="key four" data-key="4">4</div>
                    <div class="key five" data-key="5">5</div>
                    <div class="key six" data-key="6">6</div>
                    <div class="operator subtract">-</div>
                </div>
                <div class="123-row">
                    <div class="key one" data-key="1">1</div>
                    <div class="key two" data-key="2">2</div>
                    <div class="key three" data-key="3">3</div>
                    <div class="operator addition">+</div>
                </div>   
                <div class = "bottom-row">
                    <div class="key zero-key" data-key="0">0</div>
                    <div class="key decimal" data-key=".">.</div>
                    <div class="operator equals">=</div>
                </div>
            </div>
        </div>
    </div>
    
</body>
</html>