Green Lantern logo

<div a>
  <div b></div>
</div>

<style>
  body {
    background: #70ceaf;
    display: grid;
    place-content: center;
  }

  div {
    border-radius: 50%;
    border: 25px solid #0e532f;
  }

  [a] {
    width: 230px;
    height: 230px;
    display: grid;
    place-content: center;
  }
  [b] {
    width: 90px;
    height: 90px;
    position: relative;
  }

  [b]::after {
    content: '';
    width: 140px;
    height: 25px;
    background: #0e532f;
    position: absolute;
    top: -23px;
    left: 50%;
    translate: -50% -50%;
    box-shadow: 0 135px #0e532f;
  }
</style>