body {
	font-family: Roboto, "Helvetica Neue", sans-serif;
}

#canvas {
	background-color: black;
	overflow: hidden;
	width: 100%;
	height: 100%;
	position: absolute;
	top: 0px;
	left: 0px;
}

.sphere {
	position: absolute;
	border-radius: 50%;
	z-index: 1;
}

.trail {
	position: absolute;
	border-radius: 50%;
	z-index: 0;
}

.control-panel {
	position: absolute;
	color: white;
	font-size: xx-large;
	z-index: 10000;
	padding: 5px 8px;
	user-select: none;
	text-align: center;
}

.control-panel > * {
	position: relative;
	margin-right: 5px;
	cursor: pointer;
	color: inherit;
}

.control-panel > :not(span) {
	width: 32px;
}

.control-panel > i[disabled=true] {
	color: grey;
	pointer-events: none;
}

.control-panel > i[hidden=true] {
	display: none;
	margin: 0;
}

.control-panel > span {
	display: inline-block;
}

.control-panel > span.number {
	min-width: 2ch;
	pointer-events: none;
}