body {
  text-align: center;
  background: #000000; 
  color: #eee;
  font-size: 1.2em;
  font-family: sans-serif
}

img {
  max-width: 100%;
    display: block;
    margin: auto;
}

form {
    display: flex;
    justify-content: center;
    gap: 0.5em;
    flex-flow: row wrap;
    max-width: 40vw;
    margin: auto;
    align-items: baseline;
}

button[type="submit"] {
    padding: 5px 20px;
    margin: 10px auto;
    float: right;
}

#greeting {
    margin: 10px auto;
    padding: 10px 60px;
    border: 1px solid #222;
}

#greeting:empty {
    display: none;
}