body {
    margin: 25px;
    margin-top: 50px;
}

header {
    display: flex;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 50px;
    line-height: 50px;
    background-color: #eee;
}

header * {
    display: inline;
    height: 50px;
}

header ul {
    padding: 0;
}

header li {
    margin-left: 20px;
}

section {
    height: 100vh;
    border: 1px solid black;
    display: flex;
    justify-content: center;
    align-items: center;
    text-align: center;
}

#hero .profile-img {
    width: 300px;
}

footer {
    text-align: center;
    padding: 50px;
}