* {
 margin: 0;
 padding: 0;
}
 
section, article {
 padding: 2rem 2rem 0;
 max-width: 540px;
 margin: 0 auto;
}
 
ul {
 list-style-type: none;
}
 
nav ul li {
 float: right;
 margin-left: 0.5rem;
}
 
h1, h2, h3, .border {
 border-bottom: 1px solid;
}
 
h3 {
text-align: right;
}
 
.cf:after {
    content: " ";
    display: table;
    clear: both;
}