cssbattle9

<div class="b"></div>
<div class="a"></div>
<div class="c"></div>
<style>
  * {
    background: #222730;
  }
  div {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: #4CAAB3;
  }
  .a {
    width: 150px;
    height: 150px;
    transform: translate(-50%, -50%) rotate(45deg);
    outline: 50px solid #222730;
  }
  .b {
   width: 100%;
   height: 150px;
  }
  .c {
   background: #393E46;
   width: 50px;
   height: 50px;
   border-radius: 50%;
  }
</style>