CSS を使用して完全に湾曲したエッジを持つ六角形を作成するにはどうすればよいですか?

#hexagon-circle {
    width: 100px;
    height: 55px;
    background: red;
    position: relative;
    border-radius: 10px;
}
#hexagon-circle:before {
    content: "";
    position: absolute;
    top: -25px;
    left: 0;
    width: 0;
    height: 0;
    border-left: 50px solid transparent;
    border-right: 50px solid transparent;
    border-bottom: 29px solid red;
    border-radius: 10px;
}
#hexagon-circle:after {
    content: "";
    position: absolute;
    bottom: -25px;
    left: 0;
    width: 0;
    height: 0;
    border-left: 50px solid transparent;
    border-right: 50px solid transparent;
    border-top: 29px solid red;
    border-radius: 10px;
}

.hex {
  position: relative;
  margin: 1em auto;
  width: 10em;
  height: 17.32em;
  border-radius: 1em/.5em;
  background: orange;
  transition: opacity .5s;
}

.hex:before,
.hex:after {
  position: absolute;
  width: inherit;
  height: inherit;
  border-radius: inherit;
  background: inherit;
  content: '';
}

.hex:before {
  -webkit-transform: rotate(60deg);
  transform: rotate(60deg);
}

.hex:after {
  -webkit-transform: rotate(-60deg);
  transform: rotate(-60deg);
}