how to add calculator in html and css
<!DOCTYPE html>
<html>
<head>
<title>HTML and CSS Calculator</title>
<link rel="stylesheet" href="style.css">
<link href='https://fonts.googleapis.com/css?family=Orbitron' rel='stylesheet' type='text/css'>
<style>
body {
background-color: #262626;
}
.container {
top:50%;
left:50%;
position:absolute;
transform:translate(-50%,-50%);
width: 250px;
padding: 8px 8px 20px 8px;
margin: 20px auto;
background-color: #ABABAB;
border-radius: 4px;
border-top: 2px solid #FFF;
border-right: 2px solid #FFF;
border-bottom: 2px solid #C1C1C1;
border-left: 2px solid #C1C1C1;
box-shadow: -3px 3px 7px rgba(0, 0, 0, .6);
}
#display {
display: block;
margin: 15px auto;
height: 50px;
width: 250px;
padding: 0 10px;
border-radius: 4px;
border-top: 2px solid #C1C1C1;
border-right: 2px solid #C1C1C1;
border-bottom: 2px solid #FFF;
border-left: 2px solid #FFF;
background-color: #FFF;
box-shadow: inset 0px 0px 10px #030303;
font-size: 28px;
color: #000;
text-align: right;
font-weight:bold;
font-family: Orbitron;
}
.button {
display: inline-block;
margin: 3px;
width: 60px;
height: 60px;
font-size: 25px;
font-weight: bold;
border-radius: 4px;
box-sizing:border-box;
font-family: Orbitron;
}
.mathButtons {
margin: 2px 2px 6px 2px;
color: #FFF;
text-shadow: -1px -1px 0px #44006F;
background-color: #434343;
border-top: 2px solid #C1C1C1;
border-right: 2px solid #C1C1C1;
border-bottom: 2px solid #181818;
border-left: 2px solid #181818;
box-shadow: 0px 0px 2px #030303;
}
.digits {
color: #181818;
text-shadow: 1px 1px 0px #FFF;
background-color: #EBEBEB;
border-top: 2px solid #FFF;
border-right: 2px solid #FFF;
border-bottom: 2px solid #C1C1C1;
border-left: 2px solid #C1C1C1;
border-radius: 4px;
box-shadow: 0px 0px 2px #030303;
}
.digits:hover,
.mathButtons:hover,
#clearButton:hover {
background-color: #FFBA75;
box-shadow: 0px 0px 2px #FFBA75, inset 0px -20px 1px #FF8000;
border-top: 2px solid #FFF;
border-right: 2px solid #FFF;
border-bottom: 2px solid #AE5700;
border-left: 2px solid #AE5700;
}
#clearButton {
color: #FFF;
text-shadow: -1px -1px 0px #44006F;
background-color: #D20000;
border-top: 2px solid #FF8484;
border-right: 2px solid #FF8484;
border-bottom: 2px solid #800000;
border-left: 2px solid #800000;
box-shadow: 0px 0px 2px #030303, inset 0px -20px 1px #B00000;
}
</style>
</head>
<body>
<div class="wrap">
<fieldset class="container">
<form name="calculator">
<input id="display" type="text" name="display" readonly>
<input class="button digits" type="button" value="7" onclick="calculator.display.value += '7'">
<input class="button digits" type="button" value="8" onclick="calculator.display.value += '8'">
<input class="button digits" type="button" value="9" onclick="calculator.display.value += '9'">
<input class="button mathButtons" type="button" value="+" onclick="calculator.display.value += ' + '">
<br>
<input class="button digits" type="button" value="4" onclick="calculator.display.value += '4'">
<input class="button digits" type="button" value="5" onclick="calculator.display.value += '5'">
<input class="button digits" type="button" value="6" onclick="calculator.display.value += '6'">
<input class="button mathButtons" type="button" value="-" onclick="calculator.display.value += ' - '">
<br>
<input class="button digits" type="button" value="1" onclick="calculator.display.value += '1'">
<input class="button digits" type="button" value="2" onclick="calculator.display.value += '2'">
<input class="button digits" type="button" value="3" onclick="calculator.display.value += '3'">
<input class="button mathButtons" type="button" value="x" onclick="calculator.display.value += ' * '">
<br>
<input id="clearButton" class="button" type="button" value="C" onclick="calculator.display.value = ''">
<input class="button digits" type="button" value="0" onclick="calculator.display.value += '0'">
<input class="button mathButtons" type="button" value="=" onclick="calculator.display.value = eval(calculator.display.value)">
<input class="button mathButtons" type="button" value="/" onclick="calculator.display.value += ' / '">
</form>
</fieldset>
</div>
</body>
</html>