happy_flash.css

div.notice,
div.warning,
div.error {
	font-size: 18px;
	padding: 15px 10px;
	margin-bottom: 10px;
}

div.notice span, 
div.warning span,
div.error span {
	float: left;
	width: 42px;
	height: 32px;
	margin-top: -5px;
}

div.notice {
	color: #41612f; 
}
div.warning {
	color: #a26a1a;
}
div.error {
	color: #af0100;
}

happy_flash.jquery.js

flashFade = function() {
	$("div.flash").fadeOut(1500);
}

$(document).ready(function() {
	setTimeout(flashFade, 5000);
});

happy_flash_helper.rb

def happy_flash
  returning html = "" do
    flash.each do |k,v|
      html << "<div class='#{k} flash'>#{v}</div>"
    end
  end
end