<a href="#" class="button">詳しく見る</a>

.button {
  margin-bottom: 40px;
  height: 50px;
  width: 150px;
  display: grid;
  place-items: center;
  color: #fff;
  text-decoration: none;
  background-color: #000;
  position: relative;
  border: 1px solid #000;
  transition: all .6s ease;
  &:hover {
    opacity: 0.7;
  }
}