body {
max-width:75em;
margin: 0 auto;
}
nav li {
display: inline;
}
footer {font-size:0.6em;}
h1 {font-size:2.1em;
border: 1px solid;
text-align: center;
color:blue;
background-color:yellow;
}
header,footer {background-color:lightyellow;
border: 1px solid;
}
@media screen and (max-width: 600px) {
nav li {
display: block;
width: 50%;
}
}
@media only screen and (max-width : 320px) {
nav li {
width: 100%;
}
}