body{
    font-family: 'Poppins', sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: url('img.jpg') no-repeat;
    background-size: cover;
    background-position: center;
}
#container{
	width: 1000px;
	height: 600px;
	background:transparent;
	margin: 10px auto;	
}
#h1{
	font-size: 40px;
	color: #fff;
	text-align: center;
	margin-top: 0px;
}
#calculator{
	width: 320px;
	height: 520px;
	background-color: #ee520a4c;
	margin: 0 auto;
	top: 20px;
	position: relative;
	border-radius: 10px;
	box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.326), 0 6px 20px 0 rgba(0, 0, 0, 0.139);
}
#result{
	height: 120px;
}
#history{
	text-align: right;
	height: 20px;
	margin: 0 20px;
	padding-top: 10px;
	padding-bottom:10px;
	font-size: 25px;
	color: #09090a;
}
#output{
	text-align: right;
	height: 60px;
	margin: 10px 20px;
	font-size: 30px;
}
#keyboard{
	height: 400px;
}
button{
		border: none;
		cursor: pointer;
		font-weight: bold;
}
button:hover {
    box-shadow: 0px 0px 4px 4px rgba(0, 0, 0, 0.44);
}
.operator, .number, .empty{
	width: 50px;
	height: 50px;
	margin: 15px;
	float: left;
	border-radius: 50%;
	border-width: 0;
	font-weight: bold;
	font-size: 20px;
}
.number, .empty{
	background-color: #bbe0f8;
}
.number, .operator{
	cursor: pointer;
}
.operator:active, .number:active{
	font-size: 13px;
}
.operator:focus, .number:focus, .empty:focus{
	outline: 0;
}
button:nth-child(4){
	font-size: 20px;
	background-color: #20b2aa;
}
button:nth-child(8){
	font-size: 20px;
	background-color: #0ebe0e;
}
button:nth-child(12){
	font-size: 30px;
	background-color: #f13838;
}
button:nth-child(16){
	font-size: 20px;
	background-color: #7d93e0;
}
button:nth-child(17){
	font-size: 30px;
}
button:nth-child(20){
	font-size: 20px;
	background-color: #9477af;
}