I'm trying to get a round button which has a an outline in the same color but that doesn't seem to be possible. The outline always ends up squared. Is there a method to achieve that with a or does it maybe only work with a ?

button {
  width: 40px;
  height: 40px;
  border: none;
  border-radius: 40px;
  cursor: pointer;
  background-color: black;
  display: inherit;
  outline: 5px solid black;
  outline-offset: 5px;
}

<button></button>

<iframe name="sif1" sandbox="allow-forms allow-modals allow-scripts" frameborder="0"></iframe>

I have added a picture since this only seems to happen on Safari...

button {
  position: relative;
  width: 40px;
  height: 40px;
  border: none;
  border-radius: 40px;
  cursor: pointer;
  background-color: black;
  display: inherit;
  margin:10px 2px;
}

button::after {
  position: absolute;
  top: -10px;
  content: '';
  left: -10px;
  width: 50px;
  height: 50px;
  border: 5px solid black;
  border-radius: 40px;
  background-color: transparent;
  display: inherit;
}

<button></button>

<iframe name="sif2" sandbox="allow-forms allow-modals allow-scripts" frameborder="0"></iframe>