span.easy {
    background-color: lightgreen;
}
span.medium {
    background-color: yellow;
}
span.hard {
    background-color: red;
}
section.yellow {
    background-color: yellow;
}
div.green {
    background-color: lightgreen;
}
div.yellow {
    background-color: yellow;
}
div.red {
    background-color: red;
}

header, 
nav, 
section, 
article, 
aside, 
footer {
	display: block
}
nav li {
	display: inline;
	margin: 0 5px
}
nav li:first-child {
	margin-left: 0
}
nav a {
	padding: 3px 5px 3px
}
nav header {
margin-left: 0;
		font-size: 9px;
padding: 0
	}