/* ************************************************************** */
/* concept                                                        */
/* ************************************************************** */
section {
  position: relative;
  display: block;
  width: 100%;
  line-height: 0;
  overflow: hidden;
}
section::before {
  content: "";
  display: block;
}
section::after {
  content: "";
  position: absolute;
  display: block;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, .6);
}
section>img:nth-child(1) {
  position: absolute;
  top: 0;
  bottom: 0;
  margin: 0 auto;
}
section>img.description {
  position: absolute;
  display: block;
  top: 0;
  bottom: -25%;
  z-index: 1;
  opacity: 0;
  transition: bottom 1.5s, opacity 1.5s;
}
section>img.view_txt {
  bottom: 0;
  opacity: 1;
}

#section_1 {
  margin-top: 3.5em;
}

/* pc: */
@media all and (min-width: 1370px) {}
/* tab: */
@media all and (max-width: 1369px) and (min-width: 768px) {
  section>img:nth-child(2) {
    transform: scale(1.4);
  }
}
/* pc-tab */
@media all and (min-width: 768px) {
  section::before {
    padding-top: 44.3%;
  }
  section>img:nth-child(1) {
    left: 0;
    right: 0;
    width: 100%;
  }
  section>img:nth-child(2) {
    width: 50%;
    margin: auto 0;
  }
  section>img:nth-child(3) {
    display: none;
  }
  #section_1>img:nth-child(2) {
    left: 24%;
  }
  #section_2>img:nth-child(2) {
    left: 39.5%;
  }
  #section_3>img:nth-child(2) {
    left: 23%;
  }
  #section_4>img:nth-child(2) {
    left: 38%;
  }
  #section_5>img:nth-child(2) {
    left: 22.5%;
  }
}
/* tab-phone */
@media all and (max-width: 767px) {
  section::before {
    padding-top: 150%;
  }
  section>img:nth-child(1) {
    top: 0 !important;
    height: 100%;
  }
  #section_1>img:nth-child(1) {
    right: -60%;
  }
  #section_2>img:nth-child(1) {
    left: -50%;
  }
  #section_3>img:nth-child(1) {
    left: -75%;
  }
  #section_4>img:nth-child(1) {
    left: -45%;
  }
  #section_5>img:nth-child(1) {
    left: -50%;
  }
  section>img:nth-child(2) {
    display: none;
  }
  section>img:nth-child(3) {
    left: 0;
    right: 0;
    width: 95%;
    margin: auto;
  }
}