<div class="simpleButton">
  <a href="#">詳細はこちら</a>
</div>
                

.simpleButton a {
  color: #fff;
  display: inline-block;
  line-height: 1.4em;
  padding: 0.8em 3em 0.8em 2.2em;
  border-radius: 2.8em;
  position: relative;
  background: #aaa;
  background: linear-gradient(135deg, #aaa 0%, #646464 99%);
}
.simpleButton a::after {
  content: "";
  width: 0.8em;
  height: 0.8em;
  display: block;
  background: url("/img/icon/chevron-circle-right.svg") no-repeat center center;
  background-size: 100% auto;
  filter: brightness(0) saturate(100%) invert(100%) sepia(0%) saturate(0%)
    hue-rotate(228deg) brightness(106%) contrast(101%);
  position: absolute;
  top: 50%;
  right: 1.4em;
  margin-top: -0.4em;
  transition: 0.3s all ease;
}
.simpleButton a::before {
  content: "";
  border: #fff solid 1px;
  position: absolute;
  top: 2px;
  left: 2px;
  width: calc(100% - 4px);
  height: calc(100% - 4px);
  border-radius: 2.8em;
}
.simpleButton a:hover {
  color: #fff;
  opacity: 0.9;
}
.simpleButton a:hover::after {
  right: 1em;
  color: #fff;
}
              

.simpleButton a {
  color: #fff;
  display: inline-block;
  line-height: 1.4em;
  padding: 0.8em 3em 0.8em 2.2em;
  border-radius: 2.8em;
  position: relative;
  background: #aaa;
  background: linear-gradient(135deg, #aaa 0%, #646464 99%);
  &::after {
    content: "";
    width: 0.8em;
    height: 0.8em;
    display: block;
    background: url("/img/icon/chevron-circle-right.svg") no-repeat center center;
    background-size: 100% auto;
    filter: brightness(0) saturate(100%) invert(100%) sepia(0%) saturate(0%)
      hue-rotate(228deg) brightness(106%) contrast(101%);
    position: absolute;
    top: 50%;
    right: 1.4em;
    margin-top: -0.4em;
    transition: 0.3s all ease;
  }
  &::before {
    content: "";
    border: #fff solid 1px;
    position: absolute;
    top: 2px;
    left: 2px;
    width: calc(100% - 4px);
    height: calc(100% - 4px);
    border-radius: 2.8em;
  }
  &:hover {
    color: #fff;
    opacity: 0.9;
    &::after {
      right: 1em;
      color: #fff;
    }
  }
}