h1 {
    color: #FF00FF;
    text-decoration: underline;
}
main {
    width: 50%;
    margin: 0 auto;
    border: 5px groove red;
    padding: 10px;
}
header {
    border-bottom: 2px solid black;
}
#listan {
    margin-top: 120px;
}
nav > ul > li {
    list-style-type: none;
    display: inline;
}
footer {
    background-color: yellow;
}