#topMenu li a {
	position: relative;
	display: block;
	height: 21px;
	overflow: hidden;
}
#topMenu li a span {
	display: block;
	position: absolute;
	left: 50em;
	width: 50em;
}

#m1 a {
	width: 81px;
	background: url( ../images/m_dinosaurs.png ) no-repeat 0 0;
}
#m1 a:hover {
	background: url( ../images/m_dinosaurs-over.png );
}

#m2 a {
	width: 58px;
	background: url( ../images/m_biology.png ) no-repeat 0 0;
}
#m2 a:hover {
	background-image: url( ../images/m_biology-over.png );
}

#m3 a {
	width: 46px;
	background: url( ../images/m_space.png ) no-repeat 0 0;
}
#m3 a:hover {
	background-image: url( ../images/m_space-over.png );
}

#m4 a {
	width: 40px;
	background: url( ../images/m_bugs.png ) no-repeat 0 0;
}
#m4 a:hover {
	background-image: url( ../images/m_bugs-over.png );
}

#m5 a {
	width: 123px;
	background: url( ../images/m_clues.png ) no-repeat 0 0;
}
#m5 a:hover {
	background-image: url( ../images/m_clues-over.png );
}

#m6 a {
	width: 110px;
	background: url( ../images/m_exploratorium.png ) no-repeat 0 0;
}
#m6 a:hover {
	background-image: url( ../images/m_exploratorium-over.png );
}