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

.simpleButton a {
  color: #FFF;
  background: rgba(0, 0, 0, 0.6);
  line-height: 1.4;
  padding: 0.6em 2.8em 0.6em 1.5em;
  border-radius: 2.6em;
  display: inline-block;
  position: relative;
  transition: all 0.3s ease;
}
.simpleButton a::after {
  content: "";
  width: 0.8em;
  height: 0.8em;
  display: block;
  background: url("/img/icon/arrow-right.svg") no-repeat center center;
  background-size: 100% auto;
  filter: brightness(0) saturate(100%) invert(100%) sepia(0%) saturate(0%);
  position: absolute;
  top: 50%;
  right: 1.4em;
  margin-top:-0.4em;
  transition: all 0.3s ease;
}
.simpleButton a:hover{
  color: #FFF;
  background: rgba(0, 0, 0, 0.8);
}
.simpleButton a:hover::after{
  right: 1em;
}
              

.simpleButton a {
  color: #FFF;
  background: rgba(#000, 0.6);
  line-height: 1.4;
  padding: 0.6em 2.8em 0.6em 1.5em;
  border-radius: 2.6em;
  display: inline-block;
  position: relative;
  transition: all 0.3s ease;
  &::after{
    content: "";
    width: 0.8em;
    height: 0.8em;
    display: block;
    background: url("/img/icon/arrow-right.svg") no-repeat center center;
    background-size: 100% auto;
    filter: brightness(0) saturate(100%) invert(100%) sepia(0%) saturate(0%);
    position: absolute;
    top: 50%;
    right: 1.4em;
    margin-top:-0.4em;
    transition: all 0.3s ease;
  }
  &:hover{
    color: #FFF;
    background: rgba(#000, 0.8);
  }
  &:hover::after{
    right: 1em;
  }
}