button{
	padding:15px;
	border-radius:30%;
	background-color:silver;
	font-weight:bold;
	border:1px solid white;
}
header, footer{
	padding:5px;
	background-color:#0F52BA;
	color:white;
}
#calculator{
	display:grid;
	grid-template-columns:repeat(4,50px);
	gap:8px;
	justify-content:center;
}
.operator{
	background-color:slategrey;
	color:black;
	font-size:20px;
	padding:10px;
}
#display{
	background-color:silver;
	padding:10px;
	margin:10px 8px;
	height:50px;
	text-align:right;
	font-size:18px;
	border-radius:10px;
	border:1px solid white;
}
.clear{
	background-color:tomato;
	margin:5px 20px;
}
form{
	width:250px;
	border:1px solid black;
	margin:2vw auto;
	background-color:black;
	border-radius:10px;
	border:1px solid white;
	padding:5px 5px 20px 5px;
}