
      }

      .flexbox > * {
        background: yellow;
        border: 1px solid black;
        height: 20px;
      }
   </style>
  </head>
  <body>
    <!-- ZEROTH ROW: NO MARGINS -->
    <!-- No margins on flex item: -->
    <div class="flexbox">
      <div>a</div>
    </div>


    <!-- FIRST ROW: SETTING MARGIN-TOP: -->
    <br style="clear: both"/>

    <!-- auto: -->
    <div class="flexbox">
      <div style="margin-top: 18px">a</div>
    </div>

    <!-- Negative: -->
    <div class="flexbox">
  