.webp .front-page .mainimg {
  background-image: url(../img/index/webp/mv01.webp?202608);
}
.front-page .mainimg {
  background-image: url(../img/index/webp/mv01.jpg?202608);
}
@media (max-width: 480px) {
  .webp .front-page .mainimg {
    background-image: url(../img/index/webp/mv01_sp.webp?202608);
  }
  .no-webp .front-page .mainimg {
    background-image: url(../img/index/mv01_sp.jpg?202608);
  }
}