body {
    background: #000;
    color: #fff;
    font-family: 'IBM Plex Mono', monospace;
    font-weight: bold;
    text-align: center;
    height: 100dvh;
    margin: 0;
    display: flex;
}
#header {
    margin: auto;
}
#header h1 {
    margin-top: 0;
}
#header a {
    width: 100px;
    transition: 100ms;
    color: #fff;
    text-decoration: none;
    padding: 10px;
    border: #fff 2px solid;
    margin: 0 10px;
}
#header a:hover {
    background: #fff2;
}