.calculator {
	width: 400px;
	margin: 0 auto;
	margin-top: 100px;
	border: 1px solid #ccc;
	box-shadow: 0px 0px 10px #ccc;
	text-align: center;
}

.calculator input {
	height: 100px;
	padding: 0 20px;
	background-color: #252525;
	color: #fff;
	text-align: right;
	font-size: 36px;
	border: none;
	width: 100%;
	box-sizing: border-box;
}

table{
	background-color: black;
	width: 100%;
}

table,tr,td {
	border-collapse: collapse;
}

td{
	width: 25%;
}

.colspan2 {
	width: 50%;
}

button {
	width: 100%;
	height: 80px;
	font-size: 32px;
	color: #fff;
	border: none;
	background-color: grey;
	cursor: pointer;
}

.operator {
	background-color: orange;
}

button:hover {
	background-color: darkgray;
}

.operator:hover {
	background-color: darkorange;
}