style.css

body {
	background: #666;
	font-size: 12px;
	font-family: 'Lucida Sans', 'Lucida Sans Regular', 'Lucida Grande', 'Lucida Sans Unicode', Geneva, Verdana, sans-serif;
}
main {
	display: grid;
	grid-template-columns: auto auto auto;
	gap: 10px;
	position: fixed;
	left: 50%;
	top: 50%;
	transform: translate(-50%, -50%);
}
main > * {
	display: inline-block;
	width: 200px;
	padding: 20px;
	background: white;
}
fieldset {
	border: 1px solid #aaa;
	margin: 0;
	gap: 5px;
	display: grid;
}
* + fieldset {
    margin-top: 10px;
}
fieldset.slider {
	grid-template-columns: 1fr auto;
}
fieldset.split {
	grid-template-columns: 1fr 1fr;
}
fieldset.actions {
	margin-top: 20px;
	border: none;
	padding: 0;
	grid-template-columns: 2fr 3fr;
}
fieldset legend {
	font-weight: bold;
}
fieldset input {
	width: auto;
	min-width: 0;
	text-align: center;
	font-weight: bold;
}
fieldset output {
	text-align: right;
	font-weight: bold;
	min-width: 30px;
}