* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
.img-mb {
  display: none;
}
section {
  font-size: 0;
  position: relative;
  overflow: hidden;
}
section#contact .contact-item {
  width: 21.7182vw;
  height: 15.6772vw;
  position: absolute;
  top: 2.1875vw;
}
section#contact .contact-item:nth-of-type(1) {
  left: 39.8vw;
}
section#contact .contact-item:nth-of-type(2) {
  left: 62.35vw;
}
section > img {
  width: 100%;
}
.side-nav {
  width: 8vw;
  right: -8vw;
}
@media (max-width: 768px) {
  .side-nav {
    width: 100px;
    right: -100px;
  }
  .side-nav li.back-top img {
    width: 16px;
  }
  .img-pc {
    display: none;
  }
  .img-mb {
    display: inline-block;
  }
  section#contact .contact-item {
    width: calc(100vw - 50px);
    height: 47.3333vw;
    position: absolute;
  }
  section#contact .contact-item:nth-of-type(1) {
    left: 25px;
    top: 26.4vw;
  }
  section#contact .contact-item:nth-of-type(2) {
    left: 25px;
    top: 77.3333vw;
  }
}