<button></button>

* {
  box-sizing: border-box;
  padding: 0;
}
button {
  width: 60px;
  height: 60px;
  border: 1px solid transparent;
  border-radius: 50%;
  background: transparent;
  position: relative;
  &:before {
    content: '';
    position: absolute;
    top: 10px;
    left: 10px;
    right: 10px;
    bottom: 10px;
    background: #000;
    border-radius: 50%;
  }
  &:hover {
    border: 1px solid #000;
  }
}