.wrap {
  width: 100%;
  max-width: 600px;
  margin: 0 auto;
  position: relative;
}

img {
  width: 100%;
}

.bk_btn {
  width: 30%;
  /* box-shadow: 3px 5px 2px #f7cc99; */
  margin: 0 0 10px auto;
  position: absolute;
  bottom: 3%;
  right: 20px;
}
.bk_btn a {
  display: block;
  text-decoration: none;
}
.bk_btn a:hover {
  opacity: 0.7;
}