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

.simpleButton a {
  color: #FFF;
  display: inline-block;
  padding: 0.6em 2.8em 0.6em 1.5em;
  position: relative;
  border-radius: 2px;
  background-image: linear-gradient(-90deg,rgba(0,0,0,.2), rgba(0,0,0,.7));
  text-shadow: 1px 1px 2px rgba(0, 0, 0, .4);
  transition: .5s;
  background-size: 200%;
  border-radius:0.2em;
}
.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%) hue-rotate(228deg) brightness(106%) contrast(101%);
  position: absolute;
  top: 50%;
  right: 1.4em;
  margin-top:-0.5em;
  transition: all 0.5s;
}
.simpleButton a:hover {
  color: #FFF;
  background-position: right center;
}
.simpleButton a:hover::after{
  right: 1.2em;
}
              

.simpleButton a {
  color: #FFF;
  display: inline-block;
  padding: 0.6em 2.8em 0.6em 1.5em;
  position: relative;
  border-radius: 2px;
  background-image: linear-gradient(-90deg,rgba(#000,.2), rgba(#000,.7));
  text-shadow: 1px 1px 2px rgba(#000, .4);
  transition: .5s;
  background-size: 200%;
  border-radius:0.2em;
  &::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%) hue-rotate(228deg) brightness(106%) contrast(101%);
    position: absolute;
    top: 50%;
    right: 1.4em;
    margin-top:-0.5em;
    transition: all 0.5s;
  }
  &:hover {
    color: #FFF;
    background-position: right center;
    &::after{
      right: 1.2em;
    }
  }
}