View source for Template:Spoiler box/styles.css

.spoilerbox {
	margin-top: 0.6rem;
	border-radius: 8px;
	color: var( --color-base--subtle );
	background: var( --background-color-framed );
	font-size: 0.875rem;
	line-height: 1.4;
	overflow: hidden;
}

.spoilerbox-header {
	padding: 10px 15px;
	background-color: var( --border-color-base--lighter );
	letter-spacing: .75px;
	transition: background 0.2s ease;
}

.spoilerbox.mw-collapsed .spoilerbox-header {
	background: transparent;
}

.spoilerbox-content {
    padding: 10px 15px;
}

.spoilerbox .mw-collapsible-toggle:before, 
.spoilerbox .mw-collapsible-toggle:after {
	content: none;
}

.spoilerbox .mw-collapsible-text {
	display: block;
	padding: 10px 15px;
	color: var( --color-base--subtle );
    background: var( --border-color-base--lighter );
}

.spoilerbox .mw-collapsible-text:hover {
	background: var( --background-color-quiet--hover );
}

.spoilerbox .mw-collapsible-text:active {
	background: var( --background-color-quiet--active );
}
Description	What you type	What you get
Italic	''Italic text''	Italic text
Bold	'''Bold text'''	Bold text
Bold & italic	'''''Bold & italic text'''''	*Bold & italic text*