html {
    font-family: sans-serif;
}


body {
    background-color: #f5f5f5;
}

.menu {
    list-style: none;
    padding: 0;
    margin: 0;
    background-color: #333;
}

.menu li a{
    color: #fff;
    display: block;
    text-decoration: none;
    padding: .5em 1em;
}

@media screen and (min-width: 520px) {
    .menu {
        display: flex;
    }
}

#app {
    margin: auto;
    max-width: 800px;

}