.mainvisual {
  position: relative;
  margin-bottom: 75px;
  z-index: 0;
}

.mainvisual .image img {
  width: 100%;
}

@media (max-width: 767px) {
  #header {
    padding: 110px 0 60px;
  }
  #header .logo {
    width: 54.4484%;
  }
  .mainvisual {
    text-align: center;
  }
  .mainvisual .image img {
    width: 420px;
    height: 420px;
    -o-object-fit: cover;
       object-fit: cover;
  }
}