#menu_top li span.mail {
	background-image:url(../img/button_mail.png);
}
#menu_top li:hover span.mail {
	background-image:url(../img/button_mail_on.png);
}
#menu_top li span.news {
	background-image:url(../img/button_news.png);
}
#menu_top li:hover span.news {
	background-image:url(../img/button_news_on.png);
}
#menu_top li span.project {
	background-image:url(../img/button_project.png);
}
#menu_top li:hover span.project {
	background-image:url(../img/button_project_on.png);
}
#menu_top li span.stim {
	background-image:url(../img/button_stim.png);
}
#menu_top li:hover span.stim {
	background-image:url(../img/button_stim_on.png);
}