cssbattle29

<i class="t a"><i class="t b"></i></i>
<style>
  body {
    background:#F3AC3C;
    display: flex;
    align-items: center;
    justify-content: center;
  }
  .t {
    width: 200px;
    height: 200px;
  }
  .a {
    background:#1A4341;
    overflow: hidden;
    position: relative;
  }
  .b {
    background: #F3AC3C;
    border-radius: 50%;
    position: absolute;
    top: -100px;
    left: -100px;
    box-shadow: 0 200px #F3AC3C, 200px 0 #F3AC3C, 200px 200px #F3AC3C;
  }
</style>