jQuery/CSS fading overlay div that deletes itself

hover-overlay.js.coffee

$('.element').hover(
  ->
    unless $(this).children('span.overlay').length
      $(this).append('<span class="overlay"></span>')
    $('span.overlay',this).fadeIn(350)
  ,->
    $('span.overlay',this).fadeOut(350)
    window.setTimeout -> 
      $(this).children('span.overlay').remove()
      350
)

style.css

span.overlay {
	position: absolute;
	top: 0;
	left: 0;
	width: 100%;
	height: 100%;
	opacity: .3;
	background-color: lighten($blue,70%);
	display:none;
}