>
      <div class="a" style="margin-top:190px"/>
    </div>
    <div class="flexbox">
      <div class="b"/><div class="a" style="margin-top: 140px"/>
    </div>
    <div class="flexbox">
      <div class="c"
           /><div class="b" style="margin-top: 20px"
           /><div class="a" style="margin-top: 20px"/>
    </div>

    <!-- space-around -->
    <div class="flexbox">
      <div class="a" style="margin-top: 95px"/>
    </div>
    <div class="flexbox">
      <div class="b" style="margin-top: 35px"