<html>
<head>
<link rel="stylesheet" type="text/css" href="style.css">
<link href="https://fonts.googleapis.com/css?family=Open+Sans:600,700" rel="stylesheet">
<title>A simple calculator</title>
</head>
<body>
<div id="container">
<div id="calculator">
<div id="result">
<div id="history">
<p id="history-value"></p>
</div>
<div id="output">
<p id="output-value"></p>
</div>
</div>
<div id="keyboard">
<button class="operator" id="clear">C</button>
<button class="operator" id="backspace">CE</button>
<button class="operator" id="%">%</button>
<button class="operator" id="/">÷</button>
<button class="number" id="7">7</button>
<button class="number" id="8">8</button>
<button class="number" id="9">9</button>
<button class="operator" id="*">×</button>
<button class="number" id="4">4</button>
<button class="number" id="5">5</button>
<button class="number" id="6">6</button>
<button class="operator" id="-">-</button>
<button class="number" id="1">1</button>
<button class="number" id="2">2</button>
<button class="number" id="3">3</button>
<button class="operator" id="+">+</button>
<button class="empty" id="empty"></button>
<button class="number" id="0">0</button>
<button class="empty" id="empty"></button>
<button class="operator" id="=">=</button>
</div>
</div>
</div>
<script src="script.js"></script>
</body>
</html>