/* <main> is a flex column, where automatic side margins shrink the box to its content; the width keeps it filled. */
  #login {
    box-sizing: content-box;
    width: calc(100% - 2em);
    margin: 0em auto;
  }
  
  #login > h2 {
    margin-bottom: 1rem;
  }
  
  #login > a {
    display: block;
    text-align: center;
    padding-top: 1em;
  }

  @media screen and (min-width: 750px) {
    #login {
      max-width: 25em;
    }
  }