.about .hidden_show {
  height: 0;
  padding: 0;
  overflow: hidden;
  opacity: 0;
  transition: 0.8s;
}

.about input:checked~.hidden_show {
  padding: .5em 0 0;
  height: auto;
  opacity: 1;
}

.about label {
  cursor: pointer;
}

.about input {
  display: none;
}

/*	pic size
============================== */
@media all and (min-width: 768px) {
  .pic3 {
    display: flex;
  }

  .ph_cut, .ph_cut span {
    width: 820px;
    height: 230px;
  }
}

@media all and (max-width: 767px) {
  .ph_cut span {
    padding-top: calc((321 / 820)*100%);
  }
}