body {
	font-family: Arial, Helvetica, sans-serif;
	font-size: 16px;
	color: #222;
	background: #fafafa;
	margin: 0;
	display: flex;
	justify-content: center;
	align-items: center;
	min-height: 100vh;
	padding: 20px;
}

.container {
	width: 100%;
	max-width: 600px;
	background: #fff;
	padding: 20px 22px;
	border-radius: 6px;
	box-shadow: 0 1px 4px rgba(0,0,0,0.06);
}

h1 {
	font-size: 22px;
	margin: 0 0 12px 0;
}

label {
	display: block;
	margin-bottom: 6px;
}

input[type="number"] {
	padding: 8px 10px;
	font-size: 15px;
	width: 100%;
	box-sizing: border-box;
}

button {
	margin-top: 10px;
	padding: 8px 10px;
}

#result { margin-top: 14px; }