完全に湾曲したエッジを持つ CSS 六角形を作成するには?

#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);
}

<div>