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

.simpleButton a {
  color: #000;
  background: rgba(0,0,0,.2);
  border: #FFF solid 1px;
  box-shadow: 0px 0px 0px 5px rgba(0,0,0,.2);/* 外枠 */
  display: inline-block;
  position: relative;
  padding: 0.6em 3em 0.6em 1.2em;
  transition: all 0.3s ease;
  margin-bottom:5px;
}
.simpleButton a::after {
  content: "";
  width: 1.3em;
  height: 0.8em;
  display: block;
  background: url("/img/icon/long-arrow-right.svg") no-repeat center center;
  background-size: 100% auto;
  position: absolute;
  top: 50%;
  right: 1.2em;
  margin-top:-0.4em;
  transition: all 0.5s;
}
.simpleButton a:hover {
  color: #000;
  background:rgba(0,0,0,.3);
  box-shadow: 0px 0px 0px 5px rgba(0,0,0,.3);/* 外枠 */
  border: #FFF dotted 1px;
}
.simpleButton a:hover::after {
  right: 1em;
}
              

.simpleButton a {
  color: #000;
  background: rgba(#000,.2);
  border: #FFF solid 1px;
  box-shadow: 0px 0px 0px 5px rgba(#000,.2);
  display: inline-block;
  position: relative;
  padding: 0.6em 3em 0.6em 1.2em;
  transition: all 0.3s ease;
  margin-bottom:5px;
  &::after {
    content: "";
    width: 1.3em;
    height: 0.8em;
    display: block;
    background: url("/img/icon/long-arrow-right.svg") no-repeat center center;
    background-size: 100% auto;
    position: absolute;
    top: 50%;
    right: 1.2em;
    margin-top:-0.4em;
    transition: all 0.5s;
  }
  &:hover {
    color: #000;
    background:rgba(#000,.3);
    box-shadow: 0px 0px 0px 5px rgba(#000,.3);
    border: #FFF dotted 1px;
    &::after{
      right: 1em;
    }
  }
}