Letter B

<div></div>
<style>
  body {
    background: #6592cf;
    display: grid;
    place-content: center;
  }
  div {
    width: 100px;
    height: 100px;
    border: 50px solid #243d83;
    border-radius: 50%;
    border-top-color: transparent;

    rotate: -45deg;
  }

  div::after {
    content: '';
    width: 49.5px;
    height: 100px;
    position: absolute;
    background: #243d83;
    left: 7px;
    top: -88px;
    rotate: 45deg;
  }
</style>