.navigation_bar {
	border: 1px solid black;
	margin-bottom: 10px;
	padding: auto;
	background: rgba(255, 255, 255, 0.1);
}

form.search_users {
	display: inline-block;
}
.sub_menu_header {
	display: inline-block;
}
.sub_menu_header:hover {
	color: white;
	text-decoration: underline;
}
.sub_menu_header:hover .submenu {
	display: block;
}
.submenu {
	display: none;
}