ميشه بيشتر توضيح بدين ؟

کد:
a.mainlevel:link, a.mainlevel:visited {
	margin: 0;
	padding: 0 0 0 10px;
	line-height: 18px;
	text-decoration: none;
	color: #6ba9c8;
	font-weight: bold;
	font-size: 12px;
	font-family:Tahoma, Arial,sans-serif;
	background: transparent url(../images/menu_arrow.png) center right no-repeat;
}
a.mainlevel:hover {
	text-decoration: underline;
	font-weight: bold;
}