doc.silverstripe.org/sapphire/javascript/tree/tree.css

/*
 * Default CSS for tree-view
 */
ul.tree{
	width: auto;
	padding-left: 0;
	margin-left: 0;
}

ul.tree img {
	border: none;
}

ul.tree, ul.tree ul {
	padding-left: 0;
}

ul.tree ul {
	margin-left: 16px;
}

ul.tree li.closed ul {
	display: none;
}

ul.tree li {
	list-style: none;
	background: url(images/i-repeater.gif) repeat-y 1 0;
	display: block;
	width: auto;
}
	ul.tree li.last {
		list-style: none;
		background-image: none;
	}

/* Span-A: I/L/I glpyhs */
ul.tree span.a {
	background: url(images/t.gif) no-repeat 0 50%;
	display: block;
}
ul.tree .a.last {
	background: url(images/l.gif) no-repeat 0 50%;
}

/* Span-B: Plus/Minus icon */
ul.tree span.b {
}
ul.tree span.a.children span.b {
	display: inline-block;
	background: url(images/minus.gif) no-repeat 0 50%;
	cursor: pointer;
}
ul.tree li.closed span.a span.b, ul.tree span.a.unexpanded span.b {
	display: inline-block;
	background: url(images/plus.gif) no-repeat 0 50%;
	cursor: pointer;
}

/* Span-C: Spacing and extending tree line below the icon */
ul.tree span.c {
	margin-left: 16px;
}
ul.tree span.a.children span.c, ul.tree span.a.spanClosed span.c {
	background: url(images/i-bottom.gif) no-repeat 0 50%;
}
ul.tree span.a.spanClosed span.c, ul.tree span.a.unexpanded span.c {
	background-image: none;
}

/* Anchor tag: Page icon */
ul.tree span.c {
	white-space: nowrap;
}
ul.tree a {
	display: inline-block; /* IE needs this */
	white-space: pre;
	overflow: hidden;
	padding: 3px 0 1px 19px;
	line-height: 16px;
	background: url(images/page-file.png) no-repeat 0 50%;
	background-position: 0 50% !important;
	text-decoration: none;	
	outline: none;
	font-size: 11px;
}
	ul.tree a * {
		font-size: 11px;
	}
	ul.tree a:hover {
		text-decoration: underline;
	}

ul.tree span.a.spanClosed a, ul.tree span.a.Folder a {
	background-image: url(images/page-closedfolder.png);
}	
ul.tree span.a.children a {
	background-image: url(images/page-openfolder.png);
}

/* Unformatted tree */
ul.tree.unformatted li {
	background-image: none;
	padding-left: 16px;
}
ul.tree.unformatted li li {
	background-image: none;
	padding-left: 0;
}

/*
	Hover / Link tags
*/
ul.tree a:hover{
	text-decoration : none;
}

ul.tree span.a {
	cursor: pointer;
}

/*
 * Divs, by default store vertically aligned data
 */
/* As inside DIVs should be treated normally */
ul.tree div a  {
	padding: 0;
	background-image: none;
	min-height: 0;
	height: auto;
}

ul.tree li a:link,
ul.tree li a:hover,
ul.tree li a:visited {
	color: #111;
}

/*
 * Drag and drop styling
 */
ul.tree div.droppable {
	float: none;
	margin: -7px 0px -7px 16px;
	height: 10px;
	font-size: 1px;
	z-index: 1000;
}
html > body ul.tree div.droppable {
	margin: -5px 0px -5px 16px;
}

ul.tree div.droppable.dragOver {
	background: url(images/insertBetween.gif) no-repeat 50% 0;
}	

ul.tree a.dragOver, ul.tree li.dragOver a, ul.tree li.dragOver li.dragOver a {
	border: 3px solid #0074C6;
	margin: -3px;
}
ul.tree li.dragOver li a {
	border-style: none;
	margin: 0;
}

/**
 * Multiselect
 */
ul.tree span.a.current {
	font-weight: bold;
	background-color: #EEEEFF !important;
	border-top: 1px #CCCCFF solid;
	border-bottom: 1px #CCCCFF solid;	
	/* these push the highlight out to the left of the window */
	margin-left: -100px;
	padding-left: 100px;
	background-position: 100px 50%;
	/*position: relative;*/
}

ul.tree span.a.loading span.b span.c a {
	background-image: url(../../../cms/images/network-save.gif) !important;
	margin-left: -3px;
	padding-left: 21px;
	background-position : 2px 2px;
}

ul.tree.multiselect span.a span.b a {
	background-image: url(../../../cms/images/tickbox-unticked.gif) !important;
}

ul.tree.multiselect span.a.nodelete span.b a {
	background-image: url(../../../cms/images/tickbox-canttick.gif) !important;
}
ul.tree.multiselect span.a.treeloading span.b a {
	background-image: url(../../../cms/images/tickbox-greyedout.gif) !important;
}
ul.tree.multiselect span.a.failed span.b a {
	background-image: url(../../../cms/images/tickbox-fail.gif) !important;
}


ul.tree.multiselect span.a.selected span.b span.c a {
	background-image: url(../../../cms/images/tickbox-ticked.gif) !important;
}

/* Span-B: Plus/Minus icon */
ul.tree.multiselect li.selected span.a.children span.b, 
ul.tree.multiselect li.selected span.a.unexpanded span.b {
	background-image: none;
	cursor: default;
}